Mutation analysis of 5 children with primary distal renal tubular acidosis

Objective To analyze the mutations of causal genes in 5 children with primary distal renal tubular acidosis (dRTA), and explore their association of genotype and phenotype, so as to raise the awareness of the disease. Methods The whole exome sequencing was used to identify mutations in these 5 children from 5 families. Results A total of 4 different mutations of ATP6V0A4 gene were found in 2 dRTA children, including a novel heterozygous intron mutation (c.639+1G＞A), a reported heterozygous nonsense variant (c.580C＞T, p.Arg194*) and 2 novel heterozygous duplications (c.1504dupT, p.Tyr502Leufs*22; c.2351dupT, p.Phe785Ilefs*28). Two novel heterozygous missense mutations of ATP6V1B1 gene (c.409C＞T, p.Pro137Ser; c.904C＞T, p.Arg302Trp) were identified in the third child, and a heterozygous missense mutation of SLC4A1 gene (c.1765C＞A, p.Arg589Ser) previously reported was found in the fourth child. No mutation of the dRTA-related causal genes was found in the fifth child. Furthermore, the mutations of causal genes in each of the first three children were compound heterozygous, which were consistent with the autosomal recessive inheritance pattern, and the variant from the fourth child was de novo. Conclusions The present study has found 7 mutations, including 5 novel variants, which enriches the human gene mutation database (HGMD) and contributes to a better understanding of the disease mechanisms.