Intestinal enterokinase deficiency. Occurrence in two sibs and age dependency of clinical expression.

Intestinal enterokinase deficiency in 2 sibs in described. A boy failed to gain weight and had vomiting, diarrhoea, oedema, hypoproteinaemia, and anaemia in early infancy. His duodenal juice contained very low or absent proteolytic enzyme activity, which increased markedly after addition of enterokinase. He was treated with pancreatic extract and gained weight rapidly. At 44 months of age he is normal, apart from some development delay, and no longer needs pancreatic extract. His older sister, who had had similar symptoms in early infancy but then grew normally, had the same abnormality in her duodenal juice when seen at 4 years of age. Enterokinase activity was virtually absent in the duodenal mucosa of both patients. Mucosal morphology was normal. The findings suggest that enterokinase deficiency is an inherited congenital defect and not the result of mucosal damage. Affected patients may show spontaneous improvement and normal growth after the age of 6 to 12 months. This phenomenon may be related to the decreasing growth volocity during the first 2 years of life and the concimitant decrease in protein requirements per unit bodyweight.