Deficiency of galactose-1-phosphate uridyl transferase (usually written GALT deficiency) is a genetic disease where the body is missing, or has very low activity of, an enzyme needed to break down a milk sugar called galactose. This is the main cause of “classic galactosemia,” the most common and most severe form of galactosemia.
Galactose-1-phosphate uridyltransferase (GALT) deficiency, also called classic galactosemia, is a rare genetic disease where the body cannot break down a milk sugar called galactose properly. [1] Because the GALT enzyme does not work or is very low, galactose and its toxic products (like galactose-1-phosphate and galactitol) build up in the blood, liver, brain, and other organs, especially after the baby starts drinking breast milk or formula that contains lactose (glucose + galactose). [1] This build-up can cause feeding problems, vomiting, liver failure, infections, cataracts, and can be life-threatening in newborns if not treated quickly. [2] Classic galactosemia is usually inherited in an autosomal recessive pattern, which means the child gets one faulty GALT gene from each parent. [2] Newborn screening in many countries can find the disease early, and starting a galactose-restricted diet very soon after birth can prevent the life-threatening crisis, although long-term problems such as speech delay, learning difficulties, low bone density, and ovarian problems in girls can still happen. [3]
In a healthy person, lactose in milk is broken into glucose and galactose, and then several enzymes slowly change galactose into forms that the body can use for energy. In GALT deficiency, the second step of this pathway does not work, so galactose-1-phosphate and related sugars build up inside cells and damage organs such as the liver, brain, kidneys, and eyes. Without early treatment with a lactose-free and galactose-restricted diet, this buildup can cause severe illness and even death in newborn babies.
Other names
Doctors use several other names for GALT deficiency. It is also called classic galactosemia, galactosemia type I, galactose-1-phosphate uridylyltransferase deficiency, or simply GALT deficiency. All of these names describe the same condition where this one enzyme in the galactose pathway does not work properly.
Types
Even though the basic problem is the same enzyme, experts describe several types or forms, depending on how much GALT enzyme is left and how serious the symptoms are.
Classic galactosemia (severe GALT deficiency) – This is the usual and most serious form. Enzyme activity in red blood cells is almost zero, toxic sugars rise very quickly after milk feeding, and newborns can become very sick within days if they are not treated.
Clinical variant galactosemia – In this form, the baby still has some GALT activity (usually a few percent of normal), so symptoms may be milder or appear a little later, but liver disease, bleeding, and sepsis can still happen without treatment.
Duarte variant (biochemical variant) galactosemia – Here the enzyme works partly, not completely. Many children with this type have only mild or no clear symptoms, but they show abnormal lab results because GALT activity is reduced.
Causes
Medically, the true direct cause of GALT deficiency is a change (mutation) in a gene called GALT. To give 20 “causes,” this section lists different genetic changes and family situations that lead to a baby being born with too little GALT enzyme, and also some factors that increase the chance of having an affected child.
Autosomal recessive inheritance of GALT mutations – GALT deficiency follows an autosomal recessive pattern. This means a child must receive a non-working copy of the GALT gene from both parents to develop classic galactosemia.
Both parents being carriers – Most affected babies are born to parents who each carry one non-working GALT gene but are healthy themselves. When both are carriers, each pregnancy has a 25% chance to produce a child with GALT deficiency.
Severe “classic” loss-of-function GALT variants – Some specific mutations almost completely remove enzyme activity (for example commonly reported changes such as p.Gln188Arg or p.Lys285Asn in some populations). Babies who inherit two such variants usually have classic, severe disease.
Compound heterozygosity (two different mutations) – Many patients have one type of mutation on the copy from the mother and a different mutation on the copy from the father. Together these two faulty copies still lead to very low GALT activity and classic galactosemia.
Missense mutations that change one amino acid – In some families, a single “letter” change in DNA causes one amino acid in the GALT protein to be swapped for another. These missense variants may fold poorly and make the enzyme unstable or weak.
Nonsense mutations that create a stop signal – Other patients have mutations that turn a normal codon into a “stop” codon, cutting the protein short. A truncated GALT protein usually cannot do its job, so enzyme activity falls to almost zero.
Splice-site mutations – Some mutations sit at the borders of exons and introns and disturb normal RNA splicing. The cell then makes an abnormal RNA and an abnormal enzyme, again reducing GALT activity and causing disease.
Small insertions or deletions (frameshift mutations) – Adding or removing a few DNA bases can change the reading frame of the GALT gene. This usually produces a completely abnormal and non-functional enzyme, leading to severe deficiency.
Large deletions in the GALT gene – In some patients, whole exons or large segments of the GALT gene are missing. Because important parts of the protein are gone, enzyme function is lost and classic galactosemia develops.
Promoter or regulatory region changes – Mutations before the coding part of the gene (in the promoter or regulatory regions) can reduce how much GALT protein is made. Even if the protein sequence is normal, very low amounts of enzyme can be enough to cause signs of galactosemia.
Duarte variant plus a classic mutant allele – When a baby inherits one classic severe mutation and one “Duarte” partial-function mutation, the total enzyme activity is still lower than normal and can cause a biochemical form of GALT deficiency.
Ethnic founder mutations – In some ethnic groups, certain GALT mutations are very common because they started from a single ancestor (founder effect). Populations such as some European, Turkish, or Slovenian groups have characteristic high-frequency variants, which raises the number of affected children in those communities.
High carrier frequency in a population – When many people in a population carry GALT mutations, even random couples have a higher chance of both being carriers, so more babies are born with GALT deficiency.
Consanguinity (parents who are related) – When parents are blood relatives (for example, cousins), they are more likely to share the same recessive mutation. This increases the chance that a child will inherit two copies and develop GALT deficiency.
Having a previous child with galactosemia – If a couple has already had one child with classic galactosemia, this shows both are carriers, so each new pregnancy again has a 25% risk of producing a baby with GALT deficiency.
Novel or rare GALT mutations – Studies continue to discover new, previously undescribed GALT mutations in different families around the world. Many of these rare changes also reduce enzyme activity enough to cause disease.
Multiple different disease alleles in the same population – Some populations have many distinct disease-causing GALT alleles. Because there are so many possible combinations, the chance of two carriers having an affected child can be higher than expected.
Lack of or limited newborn screening programs – This does not cause the genetic defect, but in areas without newborn screening, babies with GALT deficiency may keep drinking milk for longer, so the underlying genetic problem shows itself as very severe illness.
False-negative or missed newborn screening results – Rarely, a baby with GALT deficiency may have a screening result that looks normal, especially in some clinical variant forms. If diagnosis is delayed, the same genetic problem leads to more organ damage.
High galactose intake in a baby who already has GALT deficiency – Once a baby with GALT deficiency starts milk feeds, every feed adds more galactose that cannot be processed, so toxins build up quickly and make the genetic problem much more dangerous.
Symptoms
Symptoms usually start in the first days or weeks of life after the baby begins feeding on breast milk or formula that contains lactose (and thus galactose). Severity can vary, but without treatment the illness can become life-threatening very quickly.
Feeding problems and refusal to feed – Many babies with GALT deficiency have trouble feeding; they may suck poorly, tire easily, or stop wanting milk soon after feeding starts. This is often one of the earliest warning signs.
Vomiting – Because toxic sugars irritate the gut and affect the whole body, babies often vomit after feeds. Parents may notice frequent or forceful vomiting that does not improve with simple changes in feeding.
Diarrhea – The stools can become loose and watery. Diarrhea, together with vomiting, quickly leads to dehydration and salt imbalance, which is dangerous in newborns.
Failure to thrive (poor weight gain) – Because the baby cannot use galactose for energy and often feeds poorly, weight gain is slow or stops, and growth falls off the normal growth charts.
Lethargy and extreme sleepiness – Many affected infants become unusually quiet, floppy, and difficult to wake. This “lethargy” is a sign that the brain and body are under severe stress.
Jaundice (yellow skin and eyes) – Damage to the liver stops it from clearing bilirubin normally, so the baby’s skin and the whites of the eyes turn yellow. Jaundice that is strong or lasts longer than normal newborn jaundice should always be checked.
Enlarged liver (hepatomegaly) – The liver often becomes swollen and firm because of fat, inflammation, and early scarring. A doctor can feel this on physical exam or see it on ultrasound.
Bleeding and bruising problems – The sick liver makes fewer clotting factors, so babies may bruise easily or bleed more than expected, for example from needle sticks or the umbilical stump.
Sepsis (serious blood infection), often with E. coli – Babies with untreated classic galactosemia are at high risk of severe bacterial infection, especially gram-negative sepsis such as E. coli, which can be fatal.
Hypoglycemia (low blood sugar) – Because the liver is not working well and the baby is not feeding properly, blood sugar can drop. This can cause jitteriness, sweating, or seizures.
Cataracts (clouding of the eye lens) – Galactitol made from excess galactose builds up in the lens of the eye and pulls in water, causing clouding. Cataracts may appear within weeks or months if the disease is not treated.
Swelling of the abdomen with fluid (ascites) and body swelling (edema) – Severe liver disease can cause fluid to leak into the belly and tissues, making the abdomen large and the legs or face puffy.
Developmental delay and learning difficulties – Even with early treatment, some children have delays in sitting, walking, learning in school, or understanding and using language, especially if diagnosis and diet change were late.
Speech problems, tremors, or trouble with balance (ataxia) – Older children and adults with classic galactosemia may have long-term neurologic problems, such as speech dyspraxia, shaky movements, or trouble with coordination.
Primary ovarian insufficiency in females – Many girls and women with classic galactosemia develop early ovarian failure, which can cause irregular or absent periods and problems with fertility, even when diet treatment started early.
Diagnostic tests
Physical examination
Doctors start with careful physical examination to look for signs that suggest GALT deficiency or another serious liver or metabolic problem. The physical exam does not confirm the diagnosis, but it guides urgent lab testing and treatment.
General newborn physical exam – The doctor checks the baby’s temperature, heart rate, breathing, color, hydration, and overall alertness. A sick-looking newborn with poor feeding, jaundice, and low energy after starting milk feeds makes doctors think about galactosemia and other metabolic diseases.
Abdominal examination for liver and spleen size – By gently feeling the abdomen, the doctor looks for an enlarged liver or spleen, which are very common in classic galactosemia due to liver injury and congestion.
Skin and mucous membrane examination for jaundice and bruises – The doctor inspects the skin and eyes for yellow color, small bruises, or bleeding spots that suggest liver failure and clotting problems.
Basic neurologic exam (tone, reflexes, consciousness) – Muscle tone (floppy or stiff), primitive reflexes, and level of alertness are checked to detect lethargy, irritability, or seizures, which may be part of the acute presentation in classic galactosemia.
Manual bedside and clinical tests
In addition to looking at the baby, clinicians use simple bedside and clinical tools to collect more information quickly while waiting for detailed lab studies.
Feeding and diet history review – The doctor or nurse takes a detailed history asking when milk feeds began, how long after feeds symptoms started, and whether symptoms improve when feeds are stopped. A clear link between milk feeding and worsening illness strongly suggests a problem with lactose or galactose metabolism.
Growth measurement and plotting on growth charts – The baby’s weight, length, and head size are measured and plotted. Poor weight gain or weight loss over days to weeks supports the diagnosis of a serious chronic or metabolic illness like galactosemia.
Developmental screening in older infants or children – For children diagnosed later, simple checklists of motor and language milestones help to identify developmental delay, which is a common long-term issue in classic galactosemia.
Bedside urine test for reducing substances – In some settings, a quick urine dip or older “Clinitest” tablet is used to check for sugars that can reduce copper. A positive test suggests excess galactose or other sugars, so formal lab tests for galactose and galactose-1-phosphate are then ordered.
Laboratory and pathological tests
Lab tests are essential to confirm GALT deficiency, measure how severe it is, and check for organ damage or infection.
Newborn screening dried blood spot test – In many countries, a blood spot collected from the baby’s heel is tested for galactosemia. The lab may measure total galactose, galactose-1-phosphate, and/or GALT enzyme activity. Abnormal values trigger urgent follow-up testing.
Quantitative GALT enzyme assay in red blood cells – This is a key confirmatory test. A blood sample is taken, and the lab measures exactly how much GALT enzyme activity is present in red blood cells. Classic galactosemia usually shows absent or extremely low activity.
Erythrocyte galactose-1-phosphate level – Another important test measures the amount of galactose-1-phosphate inside red blood cells. High levels support the diagnosis and are used to monitor how well a lactose-free diet is working.
Plasma or serum galactose concentration – The lab can measure free galactose in blood. Elevated values in a sick newborn who is drinking milk strongly suggest a defect in galactose metabolism such as GALT deficiency.
Urinary galactose or galactitol measurement – Excess galactose and its alcohol, galactitol, spill into the urine when GALT does not work. Measuring these helps support the diagnosis and shows the effect of diet changes over time.
Liver function tests (AST, ALT, ALP, GGT, bilirubin) – These blood tests show whether the liver is inflamed or failing. In classic galactosemia, enzymes are usually high and bilirubin is raised, fitting the picture of acute liver disease in the newborn.
Coagulation profile (PT, INR, aPTT) – Blood clotting tests often become abnormal in babies with severe liver failure due to GALT deficiency. Prolonged clotting times warn doctors about high bleeding risk and the need for urgent supportive care.
Complete blood count (CBC) and metabolic panel – A full blood count can show anemia, infection, or platelet problems, while electrolytes, kidney tests, and acid-base status reveal dehydration, kidney injury, or metabolic acidosis, all of which are common in severe galactosemia.
Blood culture and sepsis work-up – Because gram-negative sepsis (often E. coli) is a well-known complication, doctors usually take blood cultures and other sepsis tests to identify and treat any bacterial infection early.
Molecular genetic testing of the GALT gene – DNA testing can identify the exact mutations in the GALT gene. This confirms the diagnosis, helps predict severity in some cases, and allows carrier testing and prenatal diagnosis in the family.
Electrodiagnostic tests
Electrodiagnostic tests are not used to diagnose GALT deficiency itself, but they help evaluate brain and nerve problems that can occur as complications.
Electroencephalogram (EEG) – If a baby or child with galactosemia has seizures or episodes of staring and unresponsiveness, an EEG can record the brain’s electrical activity and show seizure patterns. This helps guide anti-seizure treatment and follow-up.
Nerve conduction studies and electromyography (EMG) – In older patients who develop tremors, weakness, or balance problems, nerve conduction studies and EMG can measure how well nerves and muscles carry electrical signals. They help document peripheral nerve involvement sometimes seen in long-term classic galactosemia.
Imaging tests
Imaging tests look inside the body to assess damage from GALT deficiency and to rule out other causes of the baby’s illness.
Abdominal ultrasound – Ultrasound of the abdomen is often used to view liver size, texture, and blood flow, and to check the gallbladder and spleen. In classic galactosemia it may show an enlarged, damaged liver and sometimes fluid (ascites).
Brain MRI or cranial ultrasound (in newborns) – When there are neurologic signs or developmental delay, imaging of the brain helps detect structural injury, delayed myelination, or other brain changes that can happen in severe or long-standing disease.
Ophthalmologic examination with slit-lamp (eye imaging) – An eye doctor can use a special microscope and light (slit-lamp) to see early cataracts caused by galactitol in the lens. This is a simple but very important way to assess eye involvement in galactosemia.
Non-Pharmacological Treatments (Therapies and Other Approaches)
Below are 20 non-drug treatments used to manage GALT deficiency and its long-term effects. No single therapy replaces the enzyme; they work together to protect organs, improve development, and support quality of life. [1]
Lifelong galactose-restricted diet
The main treatment is a strict diet that removes milk and most dairy products, because they contain lactose and galactose. [1] This diet usually starts as soon as the disease is suspected, even before the diagnosis is fully confirmed. It helps stop toxic galactose from building up and quickly improves liver function and general health in newborns. [1] The diet is usually lifelong, although some guidelines allow small amounts of galactose from non-milk foods later in life. [2]Lactose-free infant formula
Babies are switched from breast milk or standard formula to lactose-free products, such as soy formula or special casein-hydrolysate formulas. [1] These formulas give the baby enough calories, protein, and nutrients without the harmful sugar galactose. [2] They are usually continued through infancy and adjusted as the baby grows. [3]Specialist dietitian support and meal planning
A metabolic or pediatric dietitian helps the family plan safe meals, snacks, and drinks for every age. [1] The dietitian teaches which foods contain hidden lactose (for example, many processed foods) and how to read food labels, so accidental exposure is reduced. [2] They also check growth charts and blood tests to make sure the child gets enough protein, calories, vitamins, and minerals while following the restricted diet. [3]Newborn screening and early intervention
In many countries, newborn screening picks up classic galactosemia in the first days of life. [1] When a high screening result is found, milk is stopped and a galactose-free formula is started immediately, even before the final diagnostic tests are back. [2] Early treatment in the first days or weeks of life can prevent liver failure, severe infections, and death. [3]Regular growth and nutritional monitoring
Doctors and dietitians watch the child’s weight, height, head size, and body mass index on growth charts. [1] They also ask about appetite, bowel habits, and food variety. [2] Blood tests may check vitamins, minerals, galactose-1-phosphate, and galactitol levels to see if the diet is strict enough and if extra supplements are needed. [3]Speech and language therapy
Many children and adults with classic galactosemia have speech problems, such as apraxia (difficulty planning mouth movements) or dysarthria (slurred speech). [1] An experienced speech therapist can use exercises and communication strategies to improve speech clarity, language understanding, and social communication. [2] Early and regular therapy gives the best chance for better school performance and social confidence. [3]Physical therapy and occupational therapy
Some people develop movement problems, tremor, or coordination difficulties. [1] Physical therapists help with balance, strength, endurance, and safe movement. Occupational therapists help with fine motor skills, daily activities, school tasks, and adaptive equipment if needed. [2] Together these therapies can support independence and reduce the risk of falls or injuries. [3]Early developmental and educational support
Children with galactosemia may have learning difficulties or attention problems. [1] Early intervention programs, special education services, and learning support at school can help them reach their potential. [2] Teachers can adapt classroom tasks, extra time for tests, or visual aids to support memory and understanding. [3]Psychological and mental-health support
Living with a chronic rare disease, strict diet, and possible learning or fertility problems can cause stress, anxiety, or low mood. [1] Psychologists or counselors can help the person and family cope, build resilience, and manage worries. [2] Support groups and patient organisations also give emotional and practical help by connecting families who share similar experiences. [3]Ophthalmology follow-up for cataracts
Toxic sugar build-up can cause cataracts, especially in infancy before treatment starts. [1] Regular eye checks help to detect cataracts early and decide if they need surgery or just monitoring. [2] Early treatment of significant cataracts helps protect vision and normal development. [3]Bone-health program (exercise and lifestyle)
Many patients have low bone density and risk of osteoporosis. [1] Weight-bearing exercise (walking, running, jumping games), safe sun exposure, and a balanced diet with enough calcium and vitamin D (within the galactose-restricted plan) support bone strength. [2] Avoiding smoking and limiting alcohol in adulthood also protect bones. [3]Reproductive and fertility counselling for females
Girls and women with classic galactosemia have a high risk of primary ovarian insufficiency and may have irregular periods or infertility. [1] An endocrinologist or gynecologist can monitor hormones, discuss future family planning, and talk about options such as hormone replacement therapy or assisted reproduction. [2] Early counselling helps with realistic expectations and emotional support. [3]Genetic counselling for the family
Genetic counsellors explain the cause, inheritance pattern, and recurrence risk in future pregnancies. [1] They can discuss carrier testing for parents and siblings, and prenatal or preimplantation testing options in future pregnancies. [2] This helps families make informed choices about family planning. [3]Structured transition to adult metabolic care
As teenagers grow into adulthood, their care is often moved from pediatric specialists to adult metabolic or internal medicine teams. [1] A planned transition process helps make sure the diet, monitoring, and psychosocial support continue smoothly. [2] Clear written plans and joint pediatric–adult clinics can make this change less stressful. [3]Regular laboratory and imaging monitoring
Life-long follow-up usually includes blood and urine tests for galactose-1-phosphate, galactitol, liver function, vitamin status, and bone markers, and sometimes DXA scans for bone density. [1] This monitoring helps detect silent complications early so that diet, supplements, or other treatments can be adjusted. [2]Liver-health lifestyle advice
In older patients with past liver disease, doctors may advise avoiding alcohol, maintaining a healthy weight, and vaccinating against hepatitis A and B to protect the liver. [1] Regular follow-up of liver enzymes and ultrasound helps detect chronic damage early. [2]Vaccinations and infection-prevention planning
Newborns with classic galactosemia have a higher risk of serious infections like E. coli sepsis before treatment starts. [1] Following national vaccination schedules, prompt treatment of fevers, and clear emergency plans reduce infection risks. [2]Education about food labels and cross-contamination
Families learn how to read ingredient lists for words like “lactose,” “whey,” “milk solids,” and some additives that may contain milk. [1] They are taught to avoid cross-contamination when cooking at home and to ask about ingredients when eating out. [2] This reduces accidental galactose exposure. [3]Sick-day management plans
During illness, appetite may drop and metabolic stress increases. [1] Metabolic teams often give written “sick-day rules” including staying well hydrated, continuing the restricted diet, and seeking urgent medical help if vomiting, fever, or lethargy occur. [2] This helps prevent decompensation. [3]Use of patient-support organisations and telehealth
National and international galactosemia groups share practical guides, recipes, and emotional support. [1] Telehealth visits allow regular review with expert centers when families live far away, helping maintain high-quality care. [2]
Drug Treatments
Very important: there is no medicine that can fix the missing GALT enzyme or replace the galactose-restricted diet. [1] Drugs are used to treat or prevent complications such as liver problems, bleeding, bone loss, hormone problems, or infections. [2] All medicines and doses must be decided by a specialist doctor for each person. [3]
Below are 20 examples of drug treatments commonly used around this condition (not all are needed in every patient).
Broad-spectrum intravenous antibiotics (for neonatal sepsis)
Newborns with classic galactosemia can rapidly develop life-threatening E. coli sepsis before or just after diagnosis. [1] Doctors often give IV antibiotics such as a combination of ampicillin and gentamicin to cover common pathogens while waiting for culture results. These drugs kill bacteria or stop their growth, helping the immune system clear the infection. [2] Side effects can include allergic reactions or kidney and ear toxicity, so careful dosing and monitoring are needed. [3]Vitamin K1 (phytonadione) for bleeding and low clotting factors
Severe liver dysfunction can cause low clotting factors and bleeding. [1] Vitamin K1 (phytonadione) can be given by injection or orally to help the liver make clotting proteins and reduce bleeding risk. [2] According to FDA-approved labels, dosing is individualized and prothrombin time must be monitored to avoid over-correction and unwanted clotting. [3] Common side effects include pain at the injection site and rare allergic reactions. [4] [1]Ursodeoxycholic acid (ursodiol) for cholestatic liver disease
Some infants with galactosemia have cholestasis (poor bile flow) and elevated liver enzymes. [1] Ursodiol, a bile acid, can improve bile flow and reduce liver enzyme levels in several cholestatic conditions. [2] FDA labels suggest doses around 10–15 mg/kg/day in divided doses, but the exact dose and use are decided by specialists. [3] Side effects include diarrhea and, rarely, worsening liver tests in advanced liver disease. [4] [2]Intravenous glucose and fluids in acute crisis
During the initial crisis, IV glucose and fluids may be given to maintain blood sugar and blood pressure. [1] Glucose provides safe energy that does not rely on galactose metabolism, while fluids correct dehydration and support kidney and liver perfusion. [2] Side effects can include high blood sugar or fluid overload if not carefully monitored. [3]Folic acid supplementation
Studies show folate deficiency can develop in some children with classic galactosemia due to poor intake or absorption. [1] Folic acid tablets or syrups support red blood cell production and may modestly increase residual GALT activity, although they do not cure the defect. [2] Typical doses follow pediatric guidelines, and side effects are usually mild, such as nausea or rash. [3] [3]Calcium supplements (e.g., calcium carbonate)
Because dairy foods are restricted, many patients have low calcium intake and are at risk for weak bones. [1] Calcium supplements help maintain normal blood calcium and bone mineralization. [2] Doses are based on age and total dietary intake. Side effects can include constipation or kidney stones if doses are high or if there is kidney disease. [3]Vitamin D supplements (cholecalciferol or ergocalciferol)
Vitamin D helps the body absorb calcium and build bone. [1] Because of dietary limits and possible low sun exposure, many patients receive vitamin D drops or tablets. [2] Dosing follows general pediatric or adult bone-health guidelines, and blood levels may be monitored. Too much vitamin D can cause high calcium and kidney problems, so medical supervision is essential. [3]Bisphosphonates (e.g., alendronate) for severe osteoporosis
In adults with very low bone density or fractures, bisphosphonates such as alendronate may be used. [1] According to FDA labels, alendronate inhibits bone-resorbing cells (osteoclasts), helping to increase bone mineral density and reduce fracture risk in osteoporosis. [2] It is usually taken once weekly on an empty stomach with water, and the patient must sit upright afterwards. [3] Side effects include stomach irritation, bone or muscle pain, and rare jaw or thigh bone problems. [4] [4]Hormone replacement therapy (estrogen ± progestin) in women with ovarian insufficiency
Some adolescent girls and women need estrogen, with or without progestin, to support puberty, menstrual cycles, and bone health. [1] FDA-approved products such as estradiol or medroxyprogesterone tablets are dosed based on age, stage of puberty, and risk factors. [2] These hormones mimic natural ovarian function, but can cause side effects such as breast tenderness, mood changes, and increased risk of blood clots in some patients. [3] [5]Levothyroxine for co-existing hypothyroidism
Some individuals may also have thyroid problems unrelated or loosely related to galactosemia. [1] Levothyroxine is a synthetic thyroid hormone used to treat hypothyroidism by replacing missing hormone and normalizing metabolism. [2] FDA labeling states that doses are individualized, usually once daily on an empty stomach, and adjusted based on thyroid blood tests and symptoms. [3] Side effects of too much dose include racing heart, weight loss, and anxiety. [4] [6]Vitamin B complex and multivitamin supplements
Because the diet is restricted, multivitamin preparations that include B-vitamins, vitamin A, and others may be prescribed. [1] These help prevent general micronutrient deficiencies and support brain and nerve function. [2] Doses follow age-based recommendations, and overdose can be harmful, so products should be given only as directed by a doctor or dietitian. [3]Iron supplements if iron-deficiency anemia develops
Some patients may develop anemia due to reduced intake, heavy periods, or other causes. [1] Oral iron supplements help build up iron stores and increase hemoglobin. [2] They are usually taken for several months, and side effects can include stomach upset and dark stools. [3]Insulin or glucose-modifying drugs in rare associated diabetes
A few adults with galactosemia may also have common conditions like type 1 or type 2 diabetes, unrelated to GALT. [1] In such cases, standard diabetes drugs (for example, insulin) are used according to usual guidelines, while still respecting the galactose-restricted diet. [2] Monitoring for low blood sugar and interactions with overall nutrition is important. [3]Antiepileptic drugs if seizures occur
Rarely, neurological complications may include seizures. [1] Standard antiepileptic drugs may be used according to general epilepsy guidelines. [2] The choice of drug depends on seizure type and side-effect profile, and careful monitoring of liver function is needed if the patient has a history of liver disease. [3]Psychotropic medications for severe mood or anxiety disorders
If a person develops serious depression, anxiety, or other mental-health conditions, psychiatrists may prescribe antidepressants, anxiolytics, or other medicines, alongside psychotherapy. [1] Dosing follows standard mental-health guidelines, not specific to galactosemia, and close follow-up ensures safety and effectiveness. [2]Oral contraceptive pills for cycle control and bone health
In some adolescent girls with ovarian insufficiency, combined oral contraceptive pills may be used to regulate cycles and maintain estrogen levels for bone health. [1] These contain an estrogen and a progestin, similar in concept to hormone replacement, but dosing and goals are tailored individually. [2] Side effects may include nausea, headaches, and increased clot risk, so careful risk–benefit discussion is essential. [3]Analgesics and antipyretics (e.g., acetaminophen)
Common medicines such as acetaminophen may be used for fever or pain, following standard dosing limits and avoiding overdose. [1] They do not treat galactosemia itself, but support comfort during infections or after surgery. [2]Proton-pump inhibitors or H2 blockers if severe reflux occurs
Some children with liver disease or feeding problems may have reflux. [1] Acid-reducing drugs can protect the esophagus and improve comfort, but they should be used only when clearly needed, as long-term use has risks such as infections and nutrient malabsorption. [2]Emergency vitamin K and blood products in severe bleeding
In very severe liver failure, vitamin K alone is not enough, and doctors may give plasma or other blood products to restore clotting factors. [1] These treatments quickly replace missing proteins and can be life-saving, but carry risks such as allergic reactions and infections, so they are used in hospital settings only. [2]Other condition-specific medicines as needed
Over time, some patients may develop unrelated common diseases (like hypertension or asthma) that need usual medicines. [1] Doctors choose drugs with normal guidelines but remain alert to liver function, bone health, and possible interactions with the restricted diet. [2]
Dietary Molecular Supplements
Supplements must always be checked by the metabolic team to avoid hidden lactose/galactose and overdoses. [1]
Calcium citrate or carbonate – Supports bone building when dairy intake is limited by the diet. [1] These forms provide absorbable calcium; citrate may be easier on the stomach. Over-supplementation can cause kidney stones or constipation, so dosing is based on age and total calcium intake. [2] [7]
Vitamin D3 (cholecalciferol) – Helps the gut absorb calcium and phosphorus and supports bone mineralization. [1] Small daily or weekly doses keep blood vitamin D in the target range. Excessive doses can cause high calcium, nausea, or kidney damage, so regular monitoring is essential. [2]
Folic acid – Corrects folate deficiency, which has been observed in some children with classic galactosemia and may improve red blood cell production. [1] It works as a co-factor in DNA synthesis. Standard pediatric doses are used, and toxicity is rare but very high doses may mask vitamin B12 deficiency. [2] [8]
Vitamin B12 – Supports nerve health and red blood cell production. [1] It may be used if blood tests show low levels or high homocysteine. Injections or tablets can be used depending on absorption, and doses follow standard guidelines. [2]
General multivitamin without lactose – Provides a wide range of vitamins and sometimes minerals to cover small dietary gaps. [1] It does not replace a balanced diet but can help meet daily requirements. Care is needed to choose products without hidden lactose and to avoid double-dosing with other supplements. [2]
Omega-3 fatty acids (fish-oil or algae-based) – May support heart and brain health and reduce inflammation in general, although specific data in galactosemia are limited. [1] Doses are usually modest and taken with meals; main side effects are fishy aftertaste or mild stomach upset. [2]
Magnesium supplements – Sometimes used alongside calcium and vitamin D for bone health and muscle function. [1] Too much magnesium can cause diarrhea or, in kidney disease, serious problems, so it must be supervised. [2]
Zinc supplements (if deficient) – Zinc supports growth, immune function, and wound healing. [1] It is only given when blood tests show deficiency or poor growth. High doses can cause nausea and interfere with copper absorption. [2]
Protein supplements (lactose-free) – In older children or adults needing higher protein, lactose-free protein powders or formulas may be used. [1] They provide extra amino acids for muscle and growth without extra galactose. Careful label checking is essential to avoid hidden dairy proteins with lactose. [2]
Probiotics (lactose-free formulations) – Some clinicians use probiotics to support gut health, especially when antibiotics are needed frequently, though evidence specific to galactosemia is limited. [1] Only lactose-free products should be used, and benefits and risks should be discussed with the metabolic team. [2]
Immunity-Booster and Regenerative / Stem-Cell–Related Drugs
At present there is no approved stem-cell or gene therapy that cures classic galactosemia in routine clinical practice. [1] Research is ongoing. Below are 6 medicine-related approaches that support immunity or regeneration in a more general way. [2]
Standard childhood vaccines – While not “drugs” in the usual sense, vaccines are regulated biologicals that prime the immune system against infections. [1] Keeping all vaccines up to date is one of the most powerful “immunity-boosting” steps for children with galactosemia, especially after early sepsis. [2]
Seasonal influenza and other optional vaccines
Extra vaccines such as yearly flu shots and, when indicated, pneumococcal vaccines further reduce infection risks. [1] They work by teaching the immune system to recognise specific viruses or bacteria and respond quickly. [2]Vitamin D (immune-support role)
Besides bone health, vitamin D is involved in immune regulation. [1] Correcting deficiency may support normal immune responses, although it does not specifically treat galactosemia. [2]Planned participation in clinical trials (future gene / cell therapies)
Some research groups are exploring gene therapy or cell-based therapies for inborn errors of metabolism, but these are experimental. [1] Patients may be invited to join trials at specialised centres, where safety and benefit are monitored closely. [2]Hormone replacement (estrogen ± progestin) as tissue-support therapy
In women with ovarian insufficiency, hormone replacement does not cure GALT deficiency but supports secondary sexual characteristics, uterine health, and bone density. [1] This can be seen as a “regenerative support” for tissues otherwise harmed by hormone deficiency. [2]Bisphosphonates for bone regeneration support
Bisphosphonates such as alendronate support bone remodeling by slowing bone breakdown, allowing bone-forming cells to improve bone density. [1] They are not stem-cell drugs but are part of “regenerative” bone-health strategies in severe osteoporosis. [2]
Surgical Options
Surgery is not a primary treatment for GALT deficiency, but some complications may require operations. [1]
Cataract surgery – If cataracts caused by early galactose build-up do not improve or remain dense after starting diet, ophthalmologists may remove the cloudy lens and insert an artificial lens to restore clear vision. [1]
Liver transplantation (very rare, selected cases) – In extreme cases of irreversible liver failure despite diet and supportive care, liver transplantation might be considered. [1] It replaces the diseased liver with a donor organ, but does not completely normalise galactose metabolism throughout the body, so diet usually remains restricted. [2]
Central venous line insertion – In very sick newborns, surgeons may place central lines to give nutrition, fluids, and medicines safely over weeks. [1] This is supportive, not curative.
Orthopedic surgery for fractures or deformities – Adults with severe osteoporosis may suffer fractures that need fixation, or spine deformities that require corrective surgery. [1] These procedures stabilise bones and reduce pain.
Gynecological procedures – In women with severe gynecologic complications (such as fibroids or severe bleeding), standard gynecologic surgeries may be used. [1] These are not specific to galactosemia but must consider bone health and hormonal status.
Prevention Strategies
Newborn screening programs – Including galactosemia in national newborn screening helps detect the disease before symptoms appear. [1]
Immediate dietary restriction when suspected – Stopping galactose and starting lactose-free formula as soon as the disease is suspected can prevent the neonatal crisis. [2]
Carrier and prenatal testing in high-risk families – Knowing carrier status and using prenatal or preimplantation testing can reduce the chance of another affected child, if the family wishes. [3]
Education of health workers – Training doctors and nurses to recognize early signs (jaundice, sepsis, feeding problems) speeds diagnosis. [4]
Clear written diet plans for parents – Good written information reduces accidental exposure to galactose. [5]
Regular follow-up and lab monitoring – Continuous monitoring helps prevent long-term complications like weak bones, ovarian failure, and nutritional deficiencies. [6]
Vaccination and infection-prevention – Good vaccination coverage and quick treatment of fevers lower the chance of severe infections. [7]
Transition planning from child to adult services – Avoids gaps in care that could lead to poor diet control or missed complications. [8]
Psychosocial support – Reduces mental-health problems and improves treatment adherence. [9]
Participation in registries and research – Helps improve future prevention and management strategies by collecting long-term data. [10]
When to See Doctors
People with GALT deficiency should keep regular appointments with their metabolic team as advised (often several times in the first years, then yearly). [1] They should see a doctor urgently if there is fever, vomiting, lethargy, poor feeding, breathing trouble, jaundice, seizures, or any sudden change in behavior or consciousness. [2] Parents of newborns should treat these signs as emergencies, especially before full diagnosis and diet control. Adolescents and adults should also see doctors if they notice bone pain, fractures, menstrual problems, fertility concerns, mood changes, or learning difficulties. [3] Life-long follow-up with dietitians, endocrinologists, ophthalmologists, and other specialists is important to detect and manage complications early. [4] [11]
What to Eat and What to Avoid
Avoid all regular cow’s, goat’s, and other animal milks – They contain lactose and galactose. [1]
Avoid most standard infant formulas – Use only formulas approved by the metabolic team (soy-based or special casein-hydrolysate formulas). [2]
Avoid most dairy products – Cheese, yogurt, cream, ice cream, and butter usually contain lactose/galactose, though guidelines may allow some special low-galactose mature cheeses in older patients under dietitian control. [3]
Avoid foods with “milk,” “whey,” “casein,” “lactose,” or “milk solids” in the ingredient list – These usually contain galactose. [4]
Avoid some processed foods and sweets – Many chocolates, biscuits, sauces, and processed meats contain hidden dairy ingredients. [5]
Eat safe protein sources – Such as meat, poultry, fish, eggs, legumes, and lactose-free protein products checked by the dietitian. [6]
Eat plenty of fruits and vegetables – Most are low in galactose and provide vitamins, minerals, and fiber, though guidelines differ on exact allowances. [7]
Choose lactose-free or plant-based drinks (checked for added milk proteins) – Soy, rice, oat, or other plant drinks may be used if confirmed suitable by the team. [8]
Use lactose-free specialized products when needed – Some medicines and supplements contain lactose as a filler; lactose-free versions should be requested. [9]
Follow your country’s specific galactosemia diet guideline – Because small allowed amounts of galactose from non-milk sources may change with new research, always follow the most up-to-date advice from your metabolic centre. [10]
Frequently Asked Questions (FAQs)
Is classic galactosemia curable?
No. Classic galactosemia is a lifelong genetic condition. [1] The faulty GALT gene cannot be fixed with current standard treatments. However, a strict galactose-restricted diet started early can prevent life-threatening problems in newborns and greatly improve survival. [2] Long-term complications can still happen, so continuous follow-up is needed. [3]Can my child ever drink milk?
Standard cow’s or breast milk is unsafe for babies with classic galactosemia. [1] Some adult guidelines allow very small amounts of galactose from specific non-milk sources, and occasionally small amounts of certain mature cheeses under strict dietitian guidance, but this is carefully individualized. [2] Never change the diet without the metabolic team’s advice. [3]Why is the diet still needed if my child feels well?
Even if a person feels well, galactose can still build up in tissues and may cause long-term damage to the brain, ovaries, and bones. [1] The diet helps keep toxic substances low and is considered life-long in most guidelines. [2]Will my child have learning problems?
Many people with classic galactosemia have normal intelligence, but learning difficulties, speech problems, or attention issues are more common than in the general population. [1] Early speech therapy, educational support, and regular developmental checks can improve outcomes. [2]Can girls with galactosemia have children?
Many girls and women have reduced ovarian reserve and may have difficulty becoming pregnant, but some do conceive naturally. [1] Fertility specialists and endocrinologists can discuss options such as assisted reproductive technologies. [2] Hormone replacement is often used for health of bones and uterus even if pregnancy is not planned. [3]Do boys with galactosemia also have fertility problems?
Fertility in males with classic galactosemia appears less severely affected than in females, but data are limited. [1] Some studies report normal paternity, while others suggest possible subtle effects. [2] Regular endocrine and fertility evaluation in adulthood is recommended. [3]Is breastfeeding ever allowed?
For infants with classic galactosemia, breastfeeding is not recommended because breast milk contains lactose and galactose. [1] Once the diagnosis is confirmed, infants are usually fully switched to safe formula. [2] In some milder variants (not classic), decisions may differ, but this must always be made by specialists. [3]Can my child live a normal life expectancy?
With early diagnosis and good diet control, many people with classic galactosemia now survive into adulthood. [1] However, long-term issues (learning problems, speech disorder, ovarian insufficiency, bone disease) mean that quality of life can be affected, and continued care is needed to optimize health and independence. [2]Is newborn screening always correct?
Newborn screening for galactosemia has high sensitivity and identifies most affected babies, but false-positive and rare false-negative results can occur. [1] Confirmatory tests, including enzyme activity and genetic testing, are always required before making a final diagnosis or ruling out the disease. [2]Can adults be diagnosed for the first time?
Very rarely, milder forms or unrecognized classic cases may be diagnosed later in life, for example during investigation of cataracts, liver disease, or fertility problems. [1] In such cases, diet and monitoring are still important, although some organ damage may already have occurred. [2]Does classic galactosemia affect pregnancy in women who are already diagnosed?
Women with classic galactosemia who become pregnant continue their galactose-restricted diet and need high-risk obstetric and metabolic care. [1] Monitoring of nutrition, bone health, and hormone levels is important, and any medicines should be checked for lactose content and safety in pregnancy. [2]Are there new treatments being studied?
Researchers are looking into improved diet guidelines, new ways to monitor toxic metabolites, and potential gene or enzyme therapies, but these are still in research or very early clinical stages. [1] Patients can ask their specialists about registries or trials that may be appropriate. [2]Can my child play sports?
In most cases, children with classic galactosemia can play normal sports and be active, which is good for bone and general health. [1] If there are specific complications like severe osteoporosis, the doctor may suggest low-impact activities and protective measures. [2]Do medicines and supplements need to be lactose-free?
Yes, when possible, medicines and supplements should be checked for lactose or other milk-derived excipients. [1] Pharmacists can help find lactose-free versions, and the metabolic team decides how strict to be based on current guidelines. [2]Who should coordinate my care?
Care is best coordinated by a metabolic or inherited-metabolic-disease specialist, working together with dietitians, endocrinologists, neurologists, ophthalmologists, psychologists, and primary-care doctors. [1] A written care plan and clear communication between all team members and the family help keep management safe and consistent across life. [2]
Disclaimer: Each person’s journey is unique, treatment plan, life style, food habit, hormonal condition, immune system, chronic disease condition, geological location, weather and previous medical history is also unique. So always seek the best advice from a qualified medical professional or health care provider before trying any treatments to ensure to find out the best plan for you. This guide is for general information and educational purposes only. Regular check-ups and awareness can help to manage and prevent complications associated with these diseases conditions. If you or someone are suffering from this disease condition bookmark this website or share with someone who might find it useful! Boost your knowledge and stay ahead in your health journey. We always try to ensure that the content is regularly updated to reflect the latest medical research and treatment options. Thank you for giving your valuable time to read the article.
The article is written by Team RxHarun and reviewed by the Rx Editorial Board Members
Last Updated: January 27, 2025.
