Clinical features and SLC26A3 genetic mutation analysis of a kindred with congenital chloride diarrhea / 中华实用儿科临床杂志

Objective To analyze the clinical characteristics and mutation of SLC26A3 gene of a patient with congenital chloride diarrhea in order to deepen the understanding of the disease.Methods The clinical data of the patient who was admitted in Affiliated Hospital of Capital Pediatric Institute in June 2014 were collected.Venous blood of the proband and his parents (2 mL for each) had been extracted for genomic DNA isolation.The 21 exons of SLC26A3 gene were amplified with polymerase chain reaction and screened for mutations by sequencing.Results The main clinical features of the patient included polyhydramnios,preterm,normal birth weight,watery diarrhea,low weight and severe electrolyte disturbances with hypochloremia,hypokalemia,hyponatremia and metabolic alkalosis.Renin angiotensin and aldosterone were high.His urine chloride concentration was low and fecal chloride concentration was high (＞ 90mmol/L).After oral salt substitution therapy with KCl and NaCl [3 mmol/(kg · d),4 mmol/(kg · d)],the electrolyte was better,alkalosis was alleviated,and growth and development were improved.The gene analysis revealed that the patient carried nt1631T ＞ A homozygous mutation on exon 15 which lead to Ile544Asn mutation in the predicted SLC26A3 transmembrane protein sequence,which was considered to be responsible for the functional abnormality of the Cl-/HCO3-protein.His parents were carriers of SLC26A3 gene and their clinical phenotype was normal.Conclusions Congenital chloride diarrhea is a rare autosomal recessive disorder and easily misdiagnosed.The patient of early postnatal diarrhea with persistent hypochloremia,hypokalemia,hyponatremia and metabolic alkalosis should be thought about this disease.Genetic analysis can help make the diagnosis.The prognosis is good if a patient has an early diagnosis and appropriate management.

Identification of SLC26A3 Mutations in a Korean Patient with Congenital Chloride Diarrhea

Congenital chloride diarrhea (CLD) is an autosomal recessive disorder with the hallmark of persistent watery Cl(-)-rich diarrhea from birth. Mutations in the solute carrier family 26, member 3 (SLC26A3) gene, which encodes a coupled Cl-/HCO3- exchanger in the ileum and colon, are known to cause CLD. Although there are a few reports of CLD patients in Korea, none of these had been confirmed by genetic analysis. Here, we describe the case of a Korean infant with clinical features of CLD. Using direct sequencing analysis, we identified 2 sequence variants: a missense variant of unknown significance (c.525G>C; p.Arg175 Ser) and a splicing mutation (c.2063-1G>T) in the SLC26A3 gene; these had been inherited from the father and mother, respectively. Whilst CLD is rare, its main symptom, diarrhea, is very common in infants. Hence, the diagnosis of CLD can prove difficult. Mutational analysis of the SLC26A3 gene should be considered as a viable method to confirm a diagnosis of CLD in Korean infants with persistent diarrhea.