Analysis of mutations in the FOXI1 and KCNJ10 genes in infants with a single-allele SLC26A4 mutation

The current study investigated how the FOXI1 and KCNJ10 genes were affected in infants with a single-allele mutation in the SLC26A4 gene, and it determined the audiological phenotypes of infants with double heterozygous mutations (DHMs) in the three genes. Subjects were 562 infants with a single-allele SLC26A4 mutation detected during neonatal deafness genetic screening; the infants were seen as outpatients by Otology at Beijing Tongren Hospital. All subjects underwent SLC26A4 sequencing. Twenty infants had a second-allele variant while the remaining 542 had an SLC26A4 single-allele mutation. Infants also underwent FOXI1 and KCNJ10 sequencing. All patients with double heterozygous mutations in the aforementioned genes underwent an audiological evaluation and a limited imaging study; variants and audiological phenotypes were analyzed. Of 562 patients, 20 had SLC26A4 bi-allelic mutations; 8 carried single mutations in both SLC26A4 and KCNJ10. No pathogenic mutations in the FOXI1 gene were found. Four missense mutations in KCNJ10 were detected, including c.812G>A, c.800A>G, c.53G>A, and c.1042C>T. Eight individuals with a DHMs all passed universal newborn hearing screening, and all were found to have normal hearing. These data suggest that individuals with an SLC26A4 single-allele mutation, combined with FOXI1 or KCNJ10 gene mutations, do not suffer hearing loss during infancy, though this finding is worthy of further follow-up and in-depth discussion.