Congenital Enteropeptidase Deficiency: A Patient Guide

Congenital enteropeptidase deficiency is an exceptionally rare genetic condition that fundamentally changes how a child’s body processes the protein they eat. To understand this condition, it helps to view protein digestion as a series of steps that must happen in a specific order. Normally, when a child consumes food, the pancreas releases “inactive” protein-digesting enzymes (proteases) that are waiting to be turned on. The “starter” for this specific process is an enzyme called enteropeptidase (or enterokinase), which is produced by the lining of the small intestine ^[1]. In children with this deficiency, that starter enzyme is missing or does not work, which means the body cannot activate the enzymes needed to break down protein into the nutrients required for growth ^[2]. (Other nutrients, like certain fats and carbohydrates, are digested differently).

Because the body cannot access the protein it needs, symptoms typically emerge very early in infancy. Parents often witness a difficult cycle of chronic diarrhea, vomiting, and poor weight gain or “failure to thrive,” where a child struggles to grow despite regular feedings ^[3]. Over time, severe malnutrition and a lack of protein in the blood can lead to secondary symptoms such as edema (swelling in the limbs or abdomen), anemia, and distinctive skin rashes ^[4]. These symptoms can be deeply alarming, but they are a direct result of the body’s impaired digestion and malnutrition, rather than a lack of care or proper feeding ^[3]. (Note that anemia and rashes can have other causes, such as zinc or iron deficiency, and always require proper clinical evaluation).

This condition is an autosomal recessive genetic trait, meaning a child must inherit a variant copy of the TMPRSS15 gene from both parents to be affected ^[2]. Parents are typically “carriers” who have no symptoms themselves and may have no family history of the condition. Because it is so rare, with only a very small number of cases documented in the medical literature, the journey to a diagnosis is often long and complex, but identifying the specific cause is the key to starting the correct treatment ^[4][3].

The most vital thing for families to know is that published cases of congenital enteropeptidase deficiency show significant improvement with treatment. By using Pancreatic Enzyme Replacement Therapy (PERT), doctors can provide active enzymes, effectively bypassing the biological “block” ^[3]. Once this treatment begins, clinical turnaround in reported cases has been encouraging: diarrhea improves, swelling fades, and children often enter a period of “catch-up growth” ^[3]. While managing the condition requires a lifelong commitment to enzyme supplements and careful monitoring by specialists, it offers a path toward a healthy and thriving life for the child ^[4].