Carbohydrate-deficient glycoprotein syndrome type Ic (ALG6-CDG) is a rare, inherited disease. It happens when a gene called ALG6 does not work properly. This gene normally helps your cells add small sugar chains to proteins. That process is called N-linked glycosylation. When glycosylation is poor, many proteins do not fold or move correctly. This can affect the brain, muscles, gut, liver, eyes, hormones, growth, and blood clotting. Signs vary a lot from person to person. Some children have weak muscles (low tone), feeding problems, delays in sitting or walking, seizures, eye movement problems, and trouble with balance. A few may have gut protein loss or liver issues. The condition is present from birth because the gene change is inherited in an autosomal recessive way (both copies of the gene carry a change). Genetic Diseases Info Center+3MedlinePlus+3Orpha+3
The ALG6 enzyme normally adds the first glucose to a growing sugar chain on a lipid carrier (dolichol) in the endoplasmic reticulum. This step is needed to build the full N-glycan that later attaches to proteins. Without proper ALG6 action, the sugar chain is incomplete. That leads to “carbohydrate-deficient” glycoproteins. NCBI+2UniProt+2
ALG6-CDG is a rare, inherited condition that affects how the body adds tiny sugar chains to proteins—a process called N-linked glycosylation. In healthy cells, these sugar chains help newly made proteins fold, travel, and work properly. In ALG6-CDG, a gene called ALG6 does not work well. This gene normally helps add the first glucose sugar onto a growing sugar chain in the endoplasmic reticulum (the cell’s protein factory). When ALG6 is faulty, many proteins get the wrong sugar coat, which makes them unstable or unable to do their jobs. Because almost every organ uses glycoproteins, the condition can affect the brain, muscles, liver, hormones, blood clotting, vision, and more. Symptoms usually start in infancy, but the severity can range from mild to more serious. NCBI+2virtualglycome.org+2
Other names
Doctors and families may encounter several labels for the same disorder. Common synonyms include: ALG6-CDG, CDG-Ic, congenital disorder of glycosylation type Ic, carbohydrate-deficient glycoprotein (CDG) syndrome type Ic, CDG1C, and glucosyltransferase 1 deficiency. These all refer to the same disease caused by variants in ALG6. MedlinePlus
How the problem happens (
N-glycosylation starts by building a “starter sugar tree” (an oligosaccharide) on a lipid carrier. ALG6’s enzyme activity adds the first glucose in an alpha-1,3 bond; this is a key step toward the final Glc₃Man₉GlcNAc₂ structure that is transferred to many new proteins. ALG6 is an “inverting” glucosyltransferase that performs this step via an SN2-type reaction. If ALG6 is weak or absent, many proteins are under-glycosylated, misfold, and do not traffic normally, causing multi-system symptoms. virtualglycome.org+1
ALG6-CDG is autosomal recessive. A child is affected when they inherit one non-working ALG6 copy from each parent. Carriers (one changed copy) are usually healthy. cdghub.com
Types
There is one genetic disease here—ALG6-CDG—but people can look very different. Clinicians often talk about “types” as clinical patterns, not different diseases:
Classic infantile-onset pattern. Starts in the first year with low muscle tone (hypotonia), feeding issues, delayed milestones, and often seizures or ataxia. Liver tests and clotting tests can be abnormal. NCBI+1
Milder childhood pattern. Children may walk and talk late but improve over time. Seizures may be well-controlled or absent. School support is often needed. NCBI
Predominantly hepatic/hematologic pattern. Some have mainly liver enlargement, elevated transaminases, and blood-clotting problems with fewer neurologic signs. cdghub.com
Epilepsy-dominant pattern. A subset has a recognizable phenotype with prominent epilepsy and hypotonia. Wiley Online Library
(These are descriptive groupings used in clinics and papers to explain variability; they are not separate genetic subtypes.)
Causes
Biallelic ALG6 variants. The root cause is having disease-causing changes in both ALG6 copies. cdghub.com
Missense variants. A single “letter change” alters one amino acid, reducing enzyme function. MedlinePlus
Nonsense or frameshift variants. These create truncated, nonfunctional enzyme proteins. PMC
Splice-site variants. Changes near intron–exon borders disrupt normal mRNA splicing and enzyme levels. PubMed
Common A333V change. The c.998C>T (p.Ala333Val) missense variant is frequent in ALG6-CDG; it often reduces, but does not abolish, activity. MedlinePlus+1
Other recurrent variants. Variants like p.I299del and others are also reported in many patients worldwide. Wiley Online Library
Compound heterozygosity. Many patients inherit two different disease variants, one from each parent, leading to disease. PubMed
Founder effects. Some communities have higher rates of a specific ALG6 variant due to ancestry (e.g., A333V in certain European lineages). UbUvA Repository
Large deletions. Rarely, a bigger piece of the ALG6 gene is missing. biochemia-medica.com
Enzyme instability. Some variants leave the enzyme present but unstable at body temperature, reducing function. MedlinePlus
Endoplasmic reticulum stress. Under-glycosylated proteins misfold and can stress the ER, worsening cell function. (Mechanism of N-glycosylation defects.) NCBI
Quality-control failure. Missing glucose residues impair calnexin/calreticulin folding cycles, so proteins are degraded instead of used. NCBI
Tissue sensitivity. Brain, liver, and endocrine organs are especially sensitive to glycosylation errors, amplifying symptoms. MedlinePlus
Intercurrent illness. Fever, infections, or fasting can temporarily worsen energy balance and symptoms. (Common in CDG management.) cdghub.com
Nutritional stress. Poor intake due to feeding problems can aggravate weakness and development. fcdgc.rarediseasesnetwork.org
Hormonal changes. Puberty/hormone issues in CDG may modify symptoms like growth and energy. Metabolic Support UK
Coagulation defects. Under-glycosylated clotting factors can cause easy bruising or thrombosis risks, complicating care. Heft Pathology
Liver dysfunction. Affected glycoproteins in liver can raise enzymes and cause coagulopathy, affecting overall health. fcdgc.rarediseasesnetwork.org
Cardiac involvement. Some patients show weak heart muscle, which reduces exercise tolerance and growth. fcdgc.rarediseasesnetwork.org
Genetic background. Other benign variants in glycosylation genes can modify severity from person to person. (General CDG principle.) cdghub.com
Symptoms
Low muscle tone (hypotonia). Babies feel “floppy” and tire easily. fcdgc.rarediseasesnetwork.org
Delayed milestones. Sitting, standing, walking, and talking come later than usual. MedlinePlus
Seizures or epilepsy. Some children have convulsions that need anti-seizure care. Wiley Online Library
Poor coordination (ataxia). Balance is off; children may wobble or fall. NCBI
Feeding problems and poor weight gain. Reflux, choking, or slow growth are common. Orpha
Learning difficulties. Ranges from mild to more noticeable; support helps. MedlinePlus
Behavior or sleep issues. Sleep, speech, or behavior challenges may appear. fcdgc.rarediseasesnetwork.org
Vision problems. Strabismus or other visual issues can occur; eye care is important. Heft Pathology
Hearing issues. Some people have hearing loss and need audiology checks. fcdgc.rarediseasesnetwork.org
Abnormal blood clotting. Easy bruising or unusual clots can happen, so doctors watch clotting tests. Heft Pathology
Liver problems. Enlarged liver or high liver enzymes may be found on tests. fcdgc.rarediseasesnetwork.org
Heart muscle weakness. Rarely, the heart can be affected; cardiology follow-up is used if needed. fcdgc.rarediseasesnetwork.org
Short stature or growth issues. Growth can be slower than peers. MedlinePlus
Endocrine/puberty differences. Hormone changes (for example, delayed puberty in girls) may occur. Metabolic Support UK
Fat pads or inverted nipples (less common). Some CDG types show these features; doctors check for them during exams. Heft Pathology
Diagnostic tests
A) Physical examination (done in the clinic)
General pediatric exam. The doctor checks growth, muscle tone, reflexes, balance, eye movement, and feeding. This helps spot the multi-system pattern typical of CDG. MedlinePlus
Neurologic exam. Bedside testing of tone, strength, coordination, and reflexes documents hypotonia and ataxia and guides therapy goals. NCBI
Dysmorphology review. The clinician looks for features seen in CDG (e.g., fat pads, inverted nipples, strabismus) to support suspicion. Heft Pathology
Hepatosplenomegaly check. Feeling the abdomen for an enlarged liver or spleen can suggest hepatic involvement. fcdgc.rarediseasesnetwork.org
Cardiac exam. Listening for murmurs and signs of heart muscle weakness prompts further testing if needed. fcdgc.rarediseasesnetwork.org
B) “Manual” bedside tests and functional checks
Developmental assessments. Hands-on milestone testing (motor, speech, social) tracks delays and therapy progress. MedlinePlus
Gait and balance tests. Simple tasks like heel-to-toe walking or standing with feet together help document ataxia in older children. NCBI
Feeding/swallow screening. Manual oral-motor checks (suck, swallow, gag) identify kids who need feeding therapy or a swallow study. Orpha
Vision screening. Cover–uncover and tracking tests pick up strabismus or visual difficulty and trigger ophthalmology referral. Heft Pathology
Hearing screen. Clinic-based checks (otoacoustic emissions or audiometry referral) look for treatable hearing loss. fcdgc.rarediseasesnetwork.org
C) Laboratory and pathological tests
Transferrin isoform analysis (isoelectric focusing or mass spectrometry). This is the most common first-line biochemical screen for CDG; type I patterns suggest an assembly/transfer defect like ALG6-CDG. PMC+2ScienceDirect+2
Carbohydrate-deficient transferrin (CDT) by LC-MS/MS. Modern labs quantify transferrin glycoforms; results support CDG suspicion and guide next tests. Mayo Clinic Laboratories
Apolipoprotein C-III glycoform analysis. Helpful mainly when a type II pattern is suspected, but part of many CDG work-ups. cdghub.com
Routine chemistries and liver panel. Elevated AST/ALT and low albumin can appear with hepatic involvement. fcdgc.rarediseasesnetwork.org
Coagulation tests. PT/INR, aPTT, antithrombin, and related factors can be abnormal due to under-glycosylated clotting proteins. Heft Pathology
Genetic testing (ALG6). Definitive diagnosis comes from sequencing the ALG6 gene (often via an exome/genome test). Common pathogenic variants include c.998C>T (p.A333V); many others exist. MedlinePlus+1
Cell-based glycosylation studies (specialty centers). Fibroblast tests can analyze lipid-linked oligosaccharides and enzyme steps when clarification is needed. NCBI
D) Electrodiagnostic tests
EEG (electroencephalogram). Used to confirm and classify seizures and guide anti-seizure treatment; epilepsy is common in this CDG. Wiley Online Library
ECG/echocardiogram (if indicated). Checks rhythm and heart muscle function when cardiomyopathy is suspected. fcdgc.rarediseasesnetwork.org
(Optional) ERG or visual evoked responses. If vision is affected, these tests look at retinal and visual pathway function. Heft Pathology
E) Imaging tests
- Brain MRI is the most informative image test. In CDG-I disorders, MRI may show cerebellar changes or delayed myelination, but findings vary; MRI mainly helps rule out other causes of hypotonia or seizures and guide therapies. Liver ultrasound, skeletal X-rays (if growth concerns), and other targeted imaging are used based on symptoms. NCBI
Non-pharmacological treatments (therapies and others)
Goal of this section: practical, everyday supports. For each item: description, purpose, mechanism (how it helps). Evidence is largely based on expert guidelines and best practices for CDG care, adapted to ALG6-CDG’s common features. PubMed+1
Physiotherapy (developmental & strengthening).
Description: Regular sessions to improve posture, trunk control, and limb strength with play-based exercises.
Purpose: Reduce low muscle tone, prevent contractures, improve motor milestones.
Mechanism: Repeated motor practice increases neuro-muscular activation and joint range, building endurance and balance.Occupational therapy (fine motor & daily living).
Description: Training for feeding, dressing, writing, and play with adaptive tools.
Purpose: Independence in daily tasks.
Mechanism: Task-specific practice and graded assistance re-wire motor planning and coordination.Speech-language therapy (communication).
Description: Early speech therapy; consider augmentative/alternative communication (AAC) if speech is delayed.
Purpose: Better communication, reduced frustration.
Mechanism: Structured language stimulation and AAC give alternate pathways to express needs.Feeding therapy.
Description: Safe-swallow techniques, pacing, texture changes.
Purpose: Reduce choking, improve growth.
Mechanism: Swallow muscle training and sensory desensitization improve oral-motor control.Nutrition care plan.
Description: Dietitian builds high-calorie, high-protein plan; monitors vitamins and minerals.
Purpose: Healthy weight, support for healing and development.
Mechanism: Adequate energy and micronutrients support tissue growth and immune function.Gastrostomy feeding (when needed).
Description: If oral intake is unsafe or insufficient, a feeding tube to the stomach ensures nutrition.
Purpose: Prevent malnutrition and aspiration.
Mechanism: Reliable delivery of calories, fluids, and medicines bypasses oral-motor limits.Seizure safety plan & caregiver training.
Description: First-aid steps, trigger avoidance (fever, sleep loss), home rescue protocol.
Purpose: Reduce injury and hospital visits.
Mechanism: Prepared responses shorten seizure duration and complications.Vision care & low-vision supports.
Description: Regular eye exams; glasses/patching; vision therapy when indicated.
Purpose: Improve tracking and alignment; support learning.
Mechanism: Optical correction and visual exercises optimize remaining function.Hearing screening and supports.
Description: Periodic audiology checks; hearing aids if needed.
Purpose: Better language development.
Mechanism: Amplification ensures clear input during key language windows.Balance & ataxia training.
Description: Targeted PT for gait, core stability, and coordination.
Purpose: Fewer falls; more confident walking.
Mechanism: Cerebellar-style drills (tandem, obstacle, rhythmic tasks) improve motor timing.Orthotics & adaptive equipment.
Description: AFOs, walkers, standing frames, special seating.
Purpose: Alignment, stability, pressure relief.
Mechanism: External support improves biomechanics and energy efficiency.Behavioral sleep program.
Description: Fixed bedtimes, sleep hygiene, light control.
Purpose: Better sleep; fewer daytime behavior issues and seizures.
Mechanism: Regular circadian cues and reduced arousal improve sleep architecture.Education plan (IEP/learning supports).
Description: School-based accommodations, therapy in class, extra time.
Purpose: Access to curriculum; reduce stress.
Mechanism: Individualized scaffolding matches learning pace and sensory needs.Vaccination & infection-prevention routine.
Description: All routine vaccines; flu/COVID shots; hygiene; RSV prevention per local policy.
Purpose: Lower risk of serious infections.
Mechanism: Active and passive immunity reduce illness that can worsen seizures or nutrition. Annals of Translational MedicineCoagulation risk mitigation.
Description: Teach signs of bleeding/clots; hydrate during illness; peri-procedure planning.
Purpose: Safer surgeries and hospital stays.
Mechanism: Anticipates common CDG clotting-factor imbalances to prevent events. PMC+1Liver-friendly lifestyle advice.
Description: Avoid unnecessary hepatotoxic drugs; monitor labs; maintain healthy weight.
Purpose: Protect liver if mildly affected.
Mechanism: Reduces added liver stress.Constipation & reflux routines.
Description: Fiber, fluids, positioning, small frequent meals; reflux precautions.
Purpose: Comfort, appetite, growth.
Mechanism: Improves gut motility and reduces aspiration risk.Pain & spasticity positioning program.
Description: Gentle stretches; positioning; warm/cool packs.
Purpose: Comfort, better sleep, easier care.
Mechanism: Low-risk physical measures reduce muscle guarding.Care coordination & genetic counseling.
Description: Create a care team (neurology, GI, nutrition, PT/OT/SLT, ophthalmology, hematology, genetics). Provide family planning advice.
Purpose: Fewer gaps; informed decisions.
Mechanism: Multidisciplinary oversight for a multisystem disorder. NCBIEmergency letters & hospitalization plans.
Description: A concise document listing diagnosis, seizure plan, clotting risks, feeding needs, and medications.
Purpose: Faster, safer emergency care.
Mechanism: Standardized information supports time-critical decisions. filiere-g2m.fr
Drug treatments
Important: No drug is proven to “fix” ALG6-CDG. Medicines are used to treat symptoms and protect organs. Dose ranges below are typical starting points and must be individualized by the clinician based on age, weight, organ function, and drug interactions.
Levetiracetam (anti-seizure).
Class: Antiepileptic. Dosage/Time: Often started low and divided twice daily; titrate to response.
Purpose: Control seizures. Mechanism: Modulates synaptic vesicle protein SV2A.
Side effects: Irritability, somnolence; rare mood changes. PubMedValproate (anti-seizure).
Class: Broad-spectrum antiepileptic. Dosage/Time: Weight-based; monitor levels.
Purpose: Seizure control. Mechanism: GABA increase; sodium/calcium channel effects.
Side effects: Liver toxicity risk, weight gain, thrombocytopenia; avoid in certain mitochondrial disorders.Clonazepam or Diazepam (rescue/adjunct).
Class: Benzodiazepine. Dosage/Time: PRN for clusters; low nightly doses in some.
Purpose: Abort prolonged seizures or relieve myoclonus.
Side effects: Sedation, tolerance, constipation.Acetazolamide (for ataxia in selected CDG).
Class: Carbonic anhydrase inhibitor. Dosage/Time: Daily divided doses; renal monitoring.
Purpose: May improve cerebellar symptoms in some CDG (evidence best in PMM2-CDG; used off-label when disabling ataxia).
Mechanism: Modulates neuronal excitability via pH/ion changes.
Side effects: Paresthesia, kidney stones, metabolic acidosis—needs monitoring. Wiley Online Library+1Melatonin (sleep).
Class: Chronobiotic. Dosage/Time: Low dose 30–60 min before bedtime.
Purpose: Better sleep quality. Mechanism: Resets circadian signaling.
Side effects: Morning drowsiness in some.Baclofen (tone/spasticity).
Class: GABA-B agonist. Dosage/Time: Start very low, divide 3–4 times daily.
Purpose: Reduce spasticity if present.
Side effects: Weakness, sedation; taper to stop.Trihexyphenidyl (dystonia, when present).
Class: Anticholinergic. Dosage/Time: Very slow titration.
Purpose: Reduce dystonic postures.
Side effects: Dry mouth, constipation, cognitive slowing.Propranolol (migraine/episodes in selected patients).
Class: Beta-blocker. Dosage/Time: Weight-based, divided doses.
Purpose: Reduce headache burden or autonomic triggers.
Side effects: Bradycardia, fatigue; avoid in asthma.Ondansetron (nausea).
Class: 5-HT3 antagonist. Dosage/Time: PRN or before feeds.
Purpose: Limit vomiting, protect nutrition.
Side effects: Constipation, QT prolongation risk.Proton-pump inhibitor or H2 blocker (reflux).
Class: Acid suppression. Dosage/Time: Daily.
Purpose: Ease reflux discomfort, protect airway.
Side effects: GI changes; monitor long-term effects.Polyethylene glycol (constipation).
Class: Osmotic laxative. Dosage/Time: Daily titrated to soft stool.
Purpose: Comfort; lessen feeding refusal.
Side effects: Bloating, cramps.Multivitamin with fat-soluble vitamins (A, D, E, K) under supervision.
Class: Vitamins. Dosage/Time: Daily; lab-guided.
Purpose: Replace deficits, support growth and clotting.
Side effects: Hypervitaminosis if overdosed.Vitamin K (when clotting tests suggest low activity).
Class: Vitamin/cofactor. Dosage/Time: Per lab and hematology guidance.
Purpose: Support coagulation.
Side effects: Rare; watch for hemolysis in G6PD deficiency.Antithrombin concentrate / other factor replacement (individualized).
Class: Plasma-derived concentrates. Dosage/Time: Per hematology in high-risk settings (surgery, central lines, thrombosis history).
Purpose: Balance clotting in CDG with low natural anticoagulants.
Side effects: Infusion reactions. PMC+1Low-dose anticoagulation (selected patients only).
Class: Heparin/LMWH. Dosage/Time: Prophylaxis during immobilization or peri-operative periods as advised by hematology.
Purpose: Thrombosis prevention when risk is high.
Side effects: Bleeding—specialist supervision required. PMCIVIG (immune support if hypogammaglobulinemia and recurrent infections).
Class: Immunoglobulin replacement. Dosage/Time: Cyclic infusions.
Purpose: Reduce severe infections.
Side effects: Headache, aseptic meningitis (rare); renal monitoring.Ursodeoxycholic acid (cholestasis, if liver affected).
Class: Bile acid. Dosage/Time: Twice daily weight-based.
Purpose: Improve bile flow and liver enzymes.
Side effects: Diarrhea.Medium-chain triglyceride (MCT) oil (malabsorption).
Class: Medical food. Dosage/Time: Mixed into meals; dietitian-guided.
Purpose: Easier fat absorption for energy.
Side effects: Loose stools if too much.Carbidopa/levodopa (selected movement issues).
Class: Dopaminergic. Dosage/Time: Slow titration in divided doses.
Purpose: Trial if parkinsonian features emerge.
Side effects: Nausea, dyskinesia.Acetaminophen or ibuprofen (pain/fever management).
Class: Analgesic/antipyretic; NSAID. Dosage/Time: Weight-based PRN.
Purpose: Comfort; fever control to reduce seizure provocation.
Side effects: Liver risk (acetaminophen overdose); stomach/kidney risk (NSAIDs)—use carefully in liver disease.
Why not mannose or galactose here? These sugar therapies help specific CDG subtypes (mannose for MPI-CDG, galactose for PGM1-CDG). They have not shown established benefit in ALG6-CDG. Care remains supportive for ALG6-CDG. Annals of Translational Medicine+1
Dietary molecular supplements
L-carnitine. Supports fatty-acid transport into mitochondria; may help energy and reduce fatigue; weight-based dosing.
Coenzyme Q10. Electron transport cofactor; may support muscle energy; divided daily dosing.
Omega-3 (EPA/DHA). Anti-inflammatory; supports brain and retinal health; daily intake with meals.
Vitamin D3. Bone and immune support; lab-guided dosing to keep level in target range.
Vitamin K (low-dose maintenance if needed). Supports clotting factor function when low.
B-complex (including folate and B12 if low). Supports blood and nerve function; replace only if deficient.
Vitamin E. Antioxidant; helps with fat-malabsorption states; monitor levels to avoid excess.
Zinc. Supports growth, taste, and immune function; avoid overdose.
Selenium. Antioxidant enzyme cofactor; replace only if low.
Probiotics (selected strains). May help stool regularity and reduce antibiotic-associated diarrhea.
Note: Evidence for many supplements in ALG6-CDG is limited; decisions should be deficiency-driven and individualized.
Immunity booster / regenerative / stem-cell–type drugs
There is no proven stem-cell or regenerative drug for ALG6-CDG at this time. Below are clinically used immune-support or replacement strategies when specific problems exist:
IVIG for documented hypogammaglobulinemia with recurrent serious infections (replacement, not a “booster”).
Vaccinations according to local schedules, plus seasonal shots (prevention, not a drug per se).
Palivizumab (where indicated) for RSV prevention in high-risk infants.
Antibiotic prophylaxis in very selected cases with repeated bacterial infections (specialist decision).
G-CSF only if clinically significant neutropenia occurs (not typical for ALG6-CDG, but used if present).
Nutritional immune support (adequate protein, vitamin D, zinc) when deficiencies are proven.
Experimental gene or cell therapies are being studied for other CDG types and concepts in glycosylation disorders, but none are established for ALG6-CDG as of now. Frontiers+1
Surgeries or procedures
Gastrostomy tube placement.
Why: When oral intake is unsafe or insufficient.
Benefit: Reliable nutrition, hydration, and medication delivery.Strabismus surgery.
Why: Persistent eye misalignment with functional impact.
Benefit: Better alignment, reduced double vision, improved visual development.Orthopedic procedures (e.g., tendon lengthening, hip stabilization).
Why: Fixed contractures or hip migration due to low tone/spasticity.
Benefit: Improved comfort, positioning, and caregiving.Port or central line placement (rare, case-by-case).
Why: Recurrent IV access for infusions (e.g., IVIG, nutrition) when needed.
Benefit: Reliable access; risk mitigation plan for thrombosis is essential in CDG. PMCAnti-reflux surgery (fundoplication) or PEG-J conversion.
Why: Severe reflux/aspiration not controlled by medicines.
Benefit: Safer feeding, fewer pneumonias.
Cardiac surgery/transplant is not routine but may be considered only in exceptional ALG6-CDG cases with severe cardiomyopathy—as isolated reports note. BioMed Central
Prevention tips
Keep vaccinations up to date; flu and COVID boosters reduce severe illness.
Build a hand-hygiene routine for the whole family.
Use a sick-day plan: extra fluids, earlier medical contact, and seizure-threshold protection during fevers.
Maintain regular sleep to lower seizure risk.
Have a seizure rescue plan and supplies ready.
Prevent constipation and reflux with daily routines to protect appetite and airway.
Before any surgery, share an “ALG6-CDG summary letter” covering clot risks, feeding needs, and meds.
Avoid dehydration (it increases thrombosis risk in disorders with clotting imbalance). PMC
Review all new medicines with your team to avoid liver-toxic or sedation-stacking combinations.
Keep regular specialist check-ups (neurology, GI/liver, hematology, ophthalmology, nutrition, therapies).
When to see a doctor urgently
New or worsening seizures, a seizure lasting >5 minutes, or repeated clusters.
Signs of dehydration, persistent vomiting, or inability to keep fluids down.
Bloody stools, black tarry stools, large bruises, severe nosebleeds, or unusual swelling in a limb (possible clot or bleeding). PMC
Breathing difficulty, repeated choking, or suspected aspiration.
Rapid worsening of jaundice, very dark urine, pale stools, or strong right-upper-abdomen pain.
Sudden trouble with balance, speech, or vision not typical for the child.
Any concern that nutrition is not enough (weight loss, very slow gain, or frequent chest infections).
What to eat and what to avoid
Eat: balanced meals with enough protein (meat, eggs, dairy, legumes) to support growth.
Eat: energy-dense foods and healthy fats; add MCT oil if the dietitian recommends it.
Eat: plenty of fruits and vegetables for fiber and vitamins.
Eat: small, frequent meals if reflux or early fullness occurs.
Eat: enough fluids; offer sips often, especially during illness.
Avoid: hard-to-chew textures; choose easy-to-swallow textures if oral-motor control is weak.
Avoid: excessive added sugar and ultra-processed snacks that displace nutritious foods.
Avoid: grapefruit if taking medicines with grapefruit interactions (ask your pharmacist).
Avoid: raw/undercooked meats or eggs when immune support is needed.
Avoid: unnecessary herbal megadoses; supplements should be supervised.
Key points parents and clinicians should know
ALG6-CDG is part of the N-linked glycosylation disorders; it usually causes multi-system features with variable severity. Orpha
The ALG6 enzyme adds the first glucose to the lipid-linked sugar chain in the ER; this step is essential for building mature N-glycans. NCBI
Targeted sugar therapies exist for other subtypes (mannose for MPI-CDG; galactose for PGM1-CDG), but not for ALG6-CDG; care is supportive. Annals of Translational Medicine+1
Coagulation abnormalities can occur in CDG; plan ahead for surgeries or immobilization. PMC+1
Research is active in CDG, including symptomatic therapies (e.g., acetazolamide for PMM2-CDG ataxia), but these data do not equal proven benefit in ALG6-CDG. Wiley Online Library+1
FAQs
1) Is ALG6-CDG the same as CDG-Ic?
Yes. ALG6-CDG is the modern name; CDG-Ic is the older label. National Organization for Rare Disorders
2) How common is it?
It is rare. Fewer than a couple hundred individuals have been reported worldwide. cdghub.com+1
3) What causes it?
Changes (variants) in both copies of the ALG6 gene. Inheritance is autosomal recessive. MedlinePlus
4) What are the most common symptoms?
Low muscle tone, developmental delay, feeding problems, seizures, eye movement or alignment issues, and sometimes balance problems. Some have gut or liver issues. MedlinePlus+1
5) How is it diagnosed?
First, a blood test shows a CDG-I pattern (transferrin glycoforms). Then genetic testing confirms ALG6 changes. NCBI
6) Can diet cure it?
No specific diet cures ALG6-CDG. Good nutrition supports growth and immunity but does not correct the glycosylation defect.
7) Do sugars like mannose or galactose help?
Not for ALG6-CDG. Those sugars help other subtypes (MPI-CDG, PGM1-CDG). Annals of Translational Medicine+1
8) What about acetazolamide?
It may help ataxia in some PMM2-CDG patients; it’s not proven for ALG6-CDG. Any trial use requires specialist oversight. Wiley Online Library
9) Will my child walk or talk?
Many children make progress with therapy; outcomes vary. Early therapies and good nutrition help maximize skills. MedlinePlus
10) Is there a risk of blood clots or bleeding?
Yes, CDG can disturb clotting factors; discuss peri-procedure plans with hematology. PMC
11) Are there vision problems?
Strabismus and retinal changes can occur; regular eye care helps. Genetic Diseases Info Center
12) Can adults have ALG6-CDG?
Yes. Symptoms may change over time; adult follow-up is important. fcdgc.rarediseasesnetwork.org
13) Are there clinical trials?
Trials exist mainly for other CDG subtypes and symptom targets; families can watch CDG consortium pages for updates. fcdgc.rarediseasesnetwork.org
14) Is genetic counseling helpful?
Yes. It explains inheritance, carrier testing, and future pregnancy options. NCBI
15) What’s the long-term outlook?
Very variable. Early coordinated care improves quality of life. Research is ongoing. BioMed Central
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: September 12, 2025.
