Delayed Diagnosis in a Male With Congenital Chloride Losing Diarrhea

Congenital chloride diarrhea is a secretory type of diarrhea, inherited in as autosomal recessive. Our case involves a 12-month-old male who initially presented in infancy and was treated with an exclusive elemental formula diet. At 12 months of age, he presented with significant hypokalemia, hypochloremia, and metabolic alkalosis. The diagnosis was established with stool electrolytes demonstrating a stool chloride of 145 mmol/L. He initially was treated with sodium and potassium supplementation and a proton pump inhibitor. Genetic testing revealed a large 4.3-kb deletion encompassing exons 15 to 17 of the SLC26A3 gene and a sequence variant of the SLC26A3 gene, c.610T>G; pTyr204Asp initially reported as a variant of unknown significance. His parents had genetic testing confirming that the deletion and sequence variant were found in opposite alleles in the patient, meaning the sequence variant is a pathogenic variant. He is maintaining stable serum electrolytes and gaining appropriate weight on oral electrolyte supplementation.