Congenital Diarrhea Caused by Mutation in DGAT1

Another names
Types
Causes
Symptoms
Diagnostic tests
Non-pharmacological treatments
Drug treatments
Dietary molecular supplements
Immunity booster, regenerative, and stem cell drugs
Surgeries
Prevention
When to see doctors
What to eat and what to avoid
FAQs

Congenital diarrhea caused by mutation in DGAT1 is a very rare inherited disease. It usually starts in the newborn period or in early infancy. The baby cannot handle fat in the normal way inside the small intestine. Because of this, the intestine becomes damaged or stressed, and the child can develop watery diarrhea, poor growth, low blood protein, dehydration, and malnutrition. Doctors often call this condition DGAT1 deficiency. It is usually inherited in an autosomal recessive pattern, which means the child receives one changed DGAT1 gene from each parent. [1]

DGAT1 is an enzyme that helps the body turn fat parts into triglycerides inside intestinal cells. This step is important for normal fat absorption. When DGAT1 does not work well, fat handling becomes abnormal, and the intestinal lining may be injured by lipid toxicity. This is why many affected infants become sick soon after milk feeding starts, because milk contains fat. Some children have severe disease, while others have a milder form, especially when the mutation leaves a little enzyme function. [2]

Congenital diarrhea caused by mutation in DGAT1 is a very rare inherited disease. It usually starts in the newborn period or early infancy. The baby often gets watery diarrhea, vomiting, poor weight gain, low blood protein, swelling, and feeding intolerance. DGAT1 is a gene that helps the small intestine turn dietary fat into triglyceride. When this gene does not work well, fat handling inside intestinal cells becomes abnormal, and this can damage the lining of the bowel and lead to protein-losing enteropathy, meaning protein leaks out into the stool. The condition is also called DGAT1 deficiency or congenital diarrhea 7 with exudative enteropathy. 1 3

DGAT1 deficiency is a genetic fat-absorption disorder. A child is usually born looking normal, but after milk feeding begins, the intestine may not handle fat correctly. This can cause ongoing diarrhea, dehydration, low albumin, vitamin deficiency, growth failure, and sometimes repeated infections because important proteins and immune factors are lost from the gut. The disease is usually inherited in an autosomal recessive pattern, which means the child receives one changed copy of the gene from each parent. Many children improve a lot after a lifelong very-low-fat diet with careful nutrition support. 1 4

Another names

This disease may be called DGAT1 deficiency, DGAT1-related congenital diarrhea, DGAT1-related enteropathy, congenital diarrheal disorder type 7, or DGAT1 deficiency with protein-losing enteropathy. These names are used because the same disease can show chronic diarrhea, intestinal protein loss, and failure to thrive. [3]

Types

Classic early-onset type means the baby develops severe watery diarrhea in the first days or weeks of life. This is the most typical form. [4]
Protein-losing enteropathy–dominant type means low albumin and body swelling are very prominent because protein leaks from the intestine. [5]
Failure-to-thrive dominant type means poor weight gain and malnutrition are the main problems, even before the diagnosis is clear. [6]
Delayed or milder type means symptoms start later or are less severe. This can happen in some missense mutations that leave partial DGAT1 activity. [7]

Causes

For this disease, the true root cause is a harmful mutation in both copies of the DGAT1 gene. The 20 causes below explain the known genetic ways this disease happens or becomes clinically severe. [8]

Biallelic DGAT1 mutation is the main cause. The child has harmful changes in both gene copies, so DGAT1 function is lost or greatly reduced. [9]
Autosomal recessive inheritance is the common inheritance pattern. Parents are usually healthy carriers, but the child receives both changed copies. [10]
Homozygous mutation means the same harmful DGAT1 change is present on both gene copies. This can cause classic disease. [11]
Compound heterozygous mutation means two different harmful DGAT1 variants are present, one from each parent. This is also a common genetic cause. [12]
Nonsense mutation can create an early stop signal in the gene, so the body makes a very short, nonworking protein. [13]
Frameshift mutation can shift the reading pattern of the gene and usually leads to severe loss of protein function. [14]
Splice-site mutation can disturb how the gene message is cut and joined, so the final protein is abnormal. [15]
Missense mutation changes one building block of the protein. Some missense variants may allow partial activity, so disease may be milder. [16]
Loss-of-function mutation is a broad term for variants that make DGAT1 stop working. This is the main disease mechanism. [17]
Marked reduction of DGAT1 expression can happen when mutations reduce how much DGAT1 protein is made in cells. [18]
Defective triglyceride synthesis in enterocytes is a direct biologic cause of symptoms. The intestinal cells cannot process fat normally. [19]
Lipotoxic injury inside intestinal cells is another important mechanism. Toxic fat intermediates may build up and damage the intestinal lining. [20]
Abnormal intestinal fat absorption worsens diarrhea and malnutrition because nutrients are not handled well. [21]
Protein-losing enteropathy is not the gene cause, but it is a central disease process caused by DGAT1 failure and explains low albumin and swelling. [22]
Milk fat exposure after birth often triggers symptoms because newborn feeding suddenly increases fat load in the intestine. [23]
Residual enzyme activity differences can influence how severe the disease becomes. Less activity usually means more severe symptoms. [24]
Consanguinity in the family can increase the chance that a child inherits the same rare recessive mutation from both parents. [25]
Family history of unexplained infant diarrhea can point to the same inherited DGAT1 disease in relatives. [26]
Variant-specific effect on the protein matters because some variants fully destroy the enzyme and others only partly reduce function. [27]
Biologic stress from high dietary long-chain fat can make symptoms worse in affected infants because the intestine cannot process that fat load normally. [28]

Symptoms

Watery diarrhea is the most common symptom. It is often persistent and starts soon after birth or early feeding. [29]
Chronic diarrhea means the loose stool does not stop and continues for weeks or months, often causing repeated hospital visits. [30]
Vomiting can happen together with diarrhea, especially when feeding intolerance is present. [31]
Failure to thrive means the baby does not gain weight or grow as expected because nutrients are lost and not absorbed well. [32]
Poor feeding or feeding intolerance is common. The baby may worsen after milk feeds because fat handling is abnormal. [33]
Dehydration can happen because large amounts of water are lost in stool. This can become dangerous in infants very quickly. [34]
Protein-losing enteropathy causes a major loss of blood proteins into the gut. It is a key clinical feature of DGAT1 deficiency. [35]
Low albumin symptoms may appear as body swelling, puffiness, or fluid imbalance because albumin is an important blood protein. [36]
Malnutrition develops because the child loses nutrients and cannot absorb normal fat well. [37]
Weight loss or very poor weight gain is common in severe disease and may be one of the earliest clues. [38]
Edema means swelling of the feet, legs, face, or body because low protein lets fluid leak into tissues. [39]
Electrolyte imbalance can happen during severe diarrhea and may disturb normal body function. [40]
Hypertriglyceridemia has been reported in many patients. It is a lab feature, but it may also help doctors recognize the disorder. [41]
Abdominal distension or stomach discomfort may happen in some children during feeding intolerance and intestinal stress. [42]
Fat-soluble vitamin deficiency effects may appear later, such as weakness or poor bone health, because long-term fat absorption is abnormal. [43]

Diagnostic tests

Doctors do not use only one test. They usually combine history, physical examination, stool tests, blood tests, endoscopy, pathology, and finally genetic testing to confirm DGAT1 deficiency. [44]

Physical exam: hydration check. The doctor looks for dry mouth, sunken eyes, poor skin turgor, and weak activity to see how much fluid the baby has lost. [45]
Physical exam: weight and growth measurement. Weight, length, and head growth are checked because failure to thrive is very common. [46]
Physical exam: edema check. The doctor looks for swelling of the face, feet, legs, or body, which can suggest low albumin from protein-losing enteropathy. [47]
Physical exam: nutrition assessment. Loss of fat under the skin, muscle wasting, and weakness may show long-term malnutrition. [48]
Manual test: feeding-response observation. Doctors carefully observe whether symptoms worsen after normal fat-containing feeds and improve with fat restriction. [49]
Manual test: stool volume and stool pattern recording. Keeping a stool diary helps show chronic watery diarrhea and can guide the work-up for congenital diarrheal disorders. [50]
Manual test: diet trial with low-fat formula or special nutrition. Improvement after dietary fat restriction is an important clinical clue in DGAT1 deficiency. [51]
Lab test: serum albumin. Low albumin is one of the most important blood findings because protein-losing enteropathy is common in this disease. [52]
Lab test: total serum protein. This helps show how much body protein has been lost and supports the diagnosis of intestinal protein loss. [53]
Lab test: serum triglycerides. Hypertriglyceridemia has been reported in many patients and can support clinical suspicion. [54]
Lab test: electrolyte panel. Sodium, potassium, chloride, and bicarbonate are checked because severe diarrhea can cause dangerous imbalance. [55]
Lab test: complete blood count. This can help show malnutrition, anemia, or signs of illness, and it is commonly used in the full evaluation of infants with chronic diarrhea. [56]
Lab test: liver function tests. These tests help rule out other diseases and check the child’s general metabolic condition during severe illness. [57]
Lab test: stool alpha-1 antitrypsin. This is a very useful test for protein-losing enteropathy because it can show abnormal protein loss into the intestine. [58]
Lab test: stool fat studies. These help assess malabsorption and support the idea that the intestine is not handling fat normally. [59]
Lab test: stool electrolytes and stool osmotic assessment. These tests are part of the standard work-up for congenital diarrhea and help classify the type of diarrhea. [60]
Pathological test: upper endoscopy with small-bowel biopsy. Doctors may look directly at the intestine and take tissue samples when congenital enteropathy is suspected. [61]
Pathological test: intestinal histology. The biopsy may help exclude other congenital enteropathies. In DGAT1 deficiency, low albumin can be present even when villous and crypt structure is relatively preserved. [62]
Electrodiagnostic / molecular test: multigene congenital diarrhea panel. This is a genetic test that checks many genes known to cause congenital diarrhea, including DGAT1. [63]
Molecular confirmation: DGAT1 sequencing or exome testing. This is the confirmatory test. Finding harmful mutations in both DGAT1 gene copies confirms the diagnosis. [64]

For DGAT1-related congenital diarrhea, imaging tests and classic nerve-muscle electrodiagnostic tests are not the main tests. This disease is mainly diagnosed by clinical clues, stool and blood studies, biopsy, and genetic testing. Imaging may still be used in some children to rule out other causes of diarrhea or complications, but it is not usually the key confirmatory tool here. [65]

Non-pharmacological treatments

Very-low-fat diet is the main treatment. This is the most important therapy supported by case reports and reviews. Many children improve when long-chain fat is reduced strongly, because less fat stress reaches the intestinal cells. This can lower diarrhea, improve albumin, and support better growth. In many reported patients, this diet worked better than standard or high-fat formulas. 1 5
Sometimes fat-free or near-fat-free feeding is needed at the start in severe cases. This is used when diarrhea is very active and protein loss is high. The purpose is to rest the intestine from the nutrient it cannot process well. The mechanism is simple: if less problematic fat enters the bowel, there is less lipotoxic injury. 3
Low-fat amino-acid formula can be very helpful in infants. Several reports describe symptom improvement after changing to a low-fat amino-acid formula, especially when other formulas failed. This kind of formula may be easier to tolerate and can provide protein while keeping fat very low. 3 6
Individualized trial of medium-chain triglyceride, especially C8 MCT, may help some children, but not all. Evidence shows mixed tolerance. Some patients do better with a carefully selected MCT plan, and a 2025 case report described remission with caprylic acid (C8) MCT oil plus very-low-fat feeding. Still, tolerance differs by mutation and by patient, so it must be supervised carefully. 1 6
Parenteral nutrition may be needed in very sick infants who cannot maintain hydration, weight, or protein levels. This gives nutrition directly into the vein. Its purpose is to bypass the bowel during severe disease. It does not fix the gene defect, but it can save life, improve growth, and correct severe malnutrition while diet is being adjusted. 2 4
Oral rehydration support is important during diarrhea flares. Children with chronic watery stools lose water and salts quickly. Oral rehydration solution helps replace sodium, water, and other electrolytes. The goal is to prevent dehydration and shock. 3
Electrolyte correction is often needed. Sodium, potassium, calcium, and other ions may fall because of diarrhea and protein-losing enteropathy. Correcting these values supports heart, nerve, muscle, and brain function. 3
Albumin infusion support is sometimes used when hypoalbuminemia is severe. Low albumin can cause swelling, weakness, and poor circulation. Albumin does not cure DGAT1 deficiency, but it can temporarily raise blood protein while the bowel disease is brought under control. 2 4
Micronutrient monitoring is essential because very-low-fat diets can cause nutrient gaps. Children may become low in vitamins, minerals, and essential fatty acids. Regular blood follow-up helps the team correct problems early. 1
Essential fatty acid monitoring is especially important. Very-low-fat diets can trigger deficiency of omega-3 and omega-6 fatty acids. Reviews recommend checking an essential fatty acid panel and adjusting oral or intravenous supplementation when needed. 1
Fat-soluble vitamin replacement through a specialist plan is often needed. Vitamins A, D, E, and K may become low when fat absorption is poor or when dietary fat is heavily restricted. These vitamins support vision, bones, immunity, nerves, and blood clotting. 1 5
High-calorie low-fat feeding plan can help catch-up growth. Since fat is restricted, calories must be replaced with tolerated protein and carbohydrate sources. This is important because many children have failure to thrive. 2 5
Frequent feeding in small amounts may improve tolerance. Smaller feeds may lower vomiting, reduce bowel stress, and improve calorie delivery. This is a practical supportive method often used in infant intestinal disorders. 3
Dietitian-guided complementary feeding is important when solid foods begin. Low-fat foods must be introduced carefully to avoid relapse. Families need specific feeding plans, because common baby foods and milk products may contain too much fat. 3
Growth monitoring using weight, length, and head circumference is part of treatment. Improvement in growth is one of the clearest signs that the nutrition plan is working. 1 6
Infection prevention matters because some children have low immunoglobulins or poor general nutrition. Hand hygiene, vaccine review, and rapid treatment of infection can lower risk. 2
Genetic counseling for the family is useful. It explains inheritance, recurrence risk in future pregnancies, and the role of genetic testing in siblings. 2
Home care education is very important. Parents need to know warning signs such as worsening diarrhea, swelling, reduced urine, lethargy, and poor feeding. Good home monitoring often prevents emergency deterioration. 2
Long-term follow-up with pediatric gastroenterology is part of the therapy itself. This rare disease changes over time, and fat tolerance may vary between children depending on residual DGAT1 activity. 3
Multidisciplinary care gives the best outcome. Many children need a pediatric gastroenterologist, metabolic or genetics specialist, dietitian, and sometimes intestinal failure team. Because the disease is rare, careful expert follow-up improves safety. 2

Drug treatments

There is no FDA-approved drug that cures DGAT1 deficiency itself. The main evidence-based treatment is diet and nutrition support, not disease-specific medicine. So the medicines below are supportive drugs or hospital products used only when clinically needed, and the exact dose must be decided by a pediatric specialist according to age, weight, severity, and the child’s lab results. Using many drugs without need can be harmful. 1 5

Teduglutide (GATTEX) may be considered only in selected children with severe intestinal failure who remain dependent on parenteral nutrition. It is a GLP-2 analog approved by the FDA for patients 1 year and older with short bowel syndrome who depend on parenteral support. It is not a DGAT1-specific drug, but it may reduce parenteral nutrition need in some intestinal failure settings. Important risks include gastrointestinal obstruction, fluid overload, biliary or pancreatic problems, and concern for growth of abnormal tissue, so specialist monitoring is required. 7
Ondansetron (ZOFRAN) may be used when vomiting is severe and prevents feeding or hydration. It is an antiemetic, not a treatment for the gene problem. Its purpose is to reduce nausea and vomiting so nutrition plans can continue. Side effects can include constipation, headache, and heart rhythm concerns in some patients. 8
Famotidine (PEPCID) may be used when reflux or acid-related upper GI symptoms complicate feeding. It is an H2 blocker and can help some hospitalized children tolerate feeding better. It does not treat protein-losing enteropathy directly. 9
Omeprazole (PRILOSEC) may be used in selected patients with reflux or acid injury. It is a proton pump inhibitor. Its role is supportive only, such as reducing acid exposure when vomiting or esophagitis is present. 10
Vitamin D replacement is often needed when deficiency is present. Some DGAT1 cases have severe malabsorption with low vitamin D. The purpose is bone support, calcium balance, and immune support. 2 5
Vitamin K replacement may be needed if absorption is poor or clotting tests become abnormal. Its purpose is to support normal blood clotting and reduce bleeding risk. A 2025 DGAT1 case used vitamin K1 supplementation as part of treatment. 1
Vitamin A supplementation may be necessary when deficiency develops on a very-low-fat diet. This supports vision, epithelial health, and immunity. 1
Vitamin E supplementation may be required because fat malabsorption can lower absorption of this antioxidant vitamin. The purpose is to support nerves and cell membranes. 5
Calcium supplementation may be used when diarrhea and malnutrition lead to low calcium or poor bone support. 3
Potassium supplementation may be required when watery stool causes potassium loss. Low potassium can worsen weakness and heart rhythm risk. 3
Sodium supplementation may be needed during heavy stool losses to maintain hydration and circulation. 3
Magnesium supplementation may be needed in prolonged diarrhea or poor nutrition states. 5
Zinc supplementation can be helpful when chronic diarrhea causes low zinc levels. Zinc supports growth, immunity, and gut repair. 5
Iron therapy may be required when iron deficiency anemia develops due to malnutrition or chronic illness. 3
Albumin infusion is a medical product used in severe hypoalbuminemia. It is supportive and temporary, but it may reduce edema and stabilize the child while definitive nutrition treatment is optimized. 2 4
Immunoglobulin infusion has been reported in some children with marked hypogammaglobulinemia or infection problems. This is not routine for all patients. 2 4
Packed red blood cell transfusion may be required if significant anemia develops. Again, this is supportive hospital care, not disease-specific treatment. 3
Parenteral multivitamin preparations may be needed when enteral intake is poor. These products support children on parenteral nutrition. 3
Parenteral trace element products may be required in intestinal failure to prevent deficiency states. 5
Lipid emulsions used in parenteral nutrition may be needed carefully in children on intravenous nutrition, but the type and amount must be individualized by an intestinal failure team because DGAT1 disease is a lipid-handling disorder. 2

Dietary molecular supplements

Omega-3 and omega-6 essential fatty acid supplementation is one of the most important supplements in DGAT1 deficiency. Because the diet is very low in fat, deficiency can develop unless these fats are replaced carefully. Reviews and case reports specifically recommend this. 1
C8 MCT oil may be used in selected cases as a tolerated energy source. Some evidence suggests caprylic acid may be better tolerated than mixed C8/C10 products in some patients, but response is individual. 1
Vitamin D supports bones and calcium balance in children with malabsorption. 1
Vitamin K supports normal blood clotting in children with poor fat absorption. 1
Vitamin A supports eyes, skin, and immune function. 5
Vitamin E supports nerve and cell health. 5
Zinc may help growth and gut healing when chronic diarrhea has depleted body stores. 5
Iron helps restore hemoglobin if iron deficiency develops. 3
Calcium supports bones, especially if vitamin D deficiency or poor nutrition is present. 3
Multivitamin/mineral supplementation is often needed because minimal-fat diets can become nutritionally incomplete without careful replacement. 5

Immunity booster, regenerative, and stem cell drugs

For this disease, there are no established immunity-booster drugs, regenerative drugs, or stem cell drugs that are proven to correct DGAT1 deficiency in routine care. Published evidence supports dietary fat restriction, nutrition support, and correction of deficiencies, not stem cell treatment. When immunoglobulin is low, doctors may sometimes give IV immunoglobulin as supportive care, but that is not a cure for the gene defect. 2 5

Surgeries

There is no standard surgery that cures DGAT1 deficiency. Surgery is not the main treatment because the disorder is metabolic and intestinal, not a structural blockage. Still, five procedures may appear in complex care: central venous line placement for parenteral nutrition, feeding tube placement for long-term controlled nutrition, line revision or replacement if catheter problems occur, endoscopy with biopsy for diagnosis, and rarely intestinal transplantation only in extreme intestinal failure situations. These are done for support or diagnosis, not to fix the DGAT1 gene. 2 5

Prevention

Because this is a genetic disease, it usually cannot be prevented after conception. Still, ten preventive steps are useful: early genetic diagnosis, family counseling, rapid treatment of diarrhea, strict low-fat feeding plan, regular growth checks, essential fatty acid monitoring, vitamin monitoring, dehydration prevention, infection prevention, and close specialist follow-up. These steps do not stop the gene mutation, but they can prevent severe malnutrition, shock, and long hospital stays. 2 5

When to see doctors

A child needs urgent medical care if there is persistent watery diarrhea, vomiting, poor feeding, weight loss, swelling, low urine output, lethargy, fever, dehydration, blood in stool, or repeated infections. Ongoing diarrhea in a young infant is never something to ignore. A specialist should also review the child if albumin is low, growth is poor, or the child cannot tolerate feeds. 2 4

What to eat and what to avoid

Children with DGAT1 deficiency usually do best with a specialist-designed very-low-fat diet. Foods and formulas are chosen to keep long-chain fat very low while still giving enough calories, protein, vitamins, and essential fatty acids. Tolerated foods may include carefully selected low-fat formula, low-fat starches, low-fat cereals, rice-based foods, and other dietitian-approved low-fat solids. What to avoid usually includes high-fat milk products, cream, butter, oils, fried foods, fatty meats, and other high-fat foods. Some children may tolerate small amounts of specific MCT products, but this must be individualized. 1 5

FAQs

1. Is DGAT1 deficiency curable? No cure exists yet, but many children improve greatly with the right diet and nutrition plan. 1

2. Is it genetic? Yes. It is usually autosomal recessive. 2

3. Does every child have diarrhea from birth? Many do in the neonatal period or early infancy, but the exact timing can vary. 2

4. Is the main treatment a drug? No. The main treatment is diet, especially very-low-fat feeding. 1

5. Can MCT always be used? No. Some children tolerate it, and some do not. 1

6. Why is albumin low? Because protein can leak from the intestine into the stool. 2

7. Can this disease cause poor growth? Yes. Failure to thrive is very common. 2

8. Why are vitamins important? Fat restriction and fat malabsorption can cause vitamin deficiency. 1

9. Is genetic testing important? Yes. It helps confirm the diagnosis and guide family counseling. 2

10. Can the child eat a normal diet later? Some children tolerate more fat than others, but many need long-term restriction. 3

11. Is surgery the usual treatment? No. Surgery is not the main therapy. 5

12. Are there FDA-approved DGAT1 medicines? No specific cure is approved; medicines are supportive. 7 9

13. Can infections happen more often? They can, especially when nutrition or immunoglobulins are low. 2

14. What is the biggest danger? Severe dehydration, malnutrition, hypoalbuminemia, and growth failure in infancy. 2 4

15. What improves prognosis the most? Early diagnosis and a carefully monitored very-low-fat nutrition plan. 1 5

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: March 31, 2025.

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