Clinical Features, Molecular Genetics, and Long-Term Outcome in Congenital Chloride Diarrhea: A Nationwide Study in Japan.

OBJECTIVE: To clarify clinical and genetic features of Japanese children with congenital chloride diarrhea (CCD). STUDY DESIGN: This was a multi-institutional, retrospective survey of 616 pediatric centers in Japan with identified patients with CCD between 2014 and 2018. Mutations involving SLC26A3 were detected by Sanger sequencing. RESULTS: Thirteen patients met all entry criteria including mutations in SLC26A3, and 14 patients satisfied clinical diagnostic criteria. Homozygous or compound heterozygous mutations in SLC26A3, including 6 novel mutations, were identified in 13 of these 14 patients (93%). The most common (detected in 7 of 13) was c.2063-1g>t. Median age at diagnosis was 1 day. Nine of the patients meeting all criteria were diagnosed as neonates (69%). Median follow-up duration was 10 years. When studied, 8 patients had <5 stools daily (62%), and all had fewer than in infancy. Only 1 patient had nephrocalcinosis, and 3 (23%) had mild chronic kidney disease. Neurodevelopment was generally good; only 1 patient required special education. Five patients (38%) received long-term sodium, potassium, and chloride supplementation. CONCLUSIONS: Early fetal ultrasound diagnosis and prompt long-term sodium, potassium, and chloride supplementation were common management features. Genetic analysis of SLC26A3 provided definitive diagnosis of CCD. In contrast with previously reported localities, c.2063-1g>t might be a founder mutation in East Asia.