Analysis of correlation between clinical phenotypes and genotypes in children with distal renal tubular acidosis

Objective To analyze the correlation between clinical phenotypes and genotypes in 6 children with primary distal renal tubular acidosis (dRTA). Methods The clinical data of 6 children confirmed as dRTA in Wuhan Children′s Hospital, Tongji Medical College, Huazhong University of Science & Technology from November 2017 to August 2019 were collected, and related auxiliary examination was performed to assess their growth and development.The venous whole blood was reserved for Trio whole exome sequencing, and full spectrum genetic disease accurate diagnosis cloud platform was applied to systematic data screening and analysis.The suspected mutations were checked by Sanger sequencing, and then the role of protein was predicted by software. Results Clinical manifestations, signs and auxiliary examination results of the 6 children accorded with the diagnostic criteria of dRTA, and the prominent characteristics was growth retardation.One case had knee valgus, one had osteoporosis, and the auxiliary examination results showed that both of them had alkaline urine, metabolic acidosis, and hypokalemia.Three children had nephrocalcinosis, and 2 children had nephrolithiasis.The parents of the 6 patients were all normal without phenotypes.Mutations in the SLC4A1 gene were identified in 4 patients, including 1 child with a reported homozygous autosomal recessive missense mutation(c.2102G>A, p.G701D), who had dRTA and hemolytic anemia, and 3 children with the reported de novo heterozygous autosomal dominant missense mutation(c.1766G>A, p.R589H, c.1765C>T, p.R589C), whose age at diagnosis was related to abnormal renal imaging.Compound heterozygous autosomal recessive mutations in the ATPV1B1 gene were identified in 1 patient, and they were novel heterozygous missense mutations (1153C>A, p.P385T and c. 806C>T, p.P269L). A novel homozygous autosomal recessive missense mutation was identified in 1 patient in the ATPV0A4 gene(c.1899C>A, p.Y633X, 208). Conclusions Mutations in SLC4A1, ATP6V1B1, ATP6V0A4 genes are identified as the main causes of the primary dRTA, and the phenotypes was related to the mutation features and genotypes.Genetic test should be conducted on patients suspected as dRTA for early molecular diagnosis, thereby improving clinical phenotypic screening and individualized treatment. Key words: Distal renal tubular acidosis; Genetic mutation; SLC4A1 gene; ATP6V1B1 gene; ATP6V0A4 gene