Analysis of TMC1 gene variants and prenatal diagnosis in four Chinese families affected with deafness

Objective To explore the genetic basis of four Chinese families affected with deafness. Methods All probands were subjected to next generation sequencing (NGS). Suspected variant were verified by Sanger sequencing among the family members. Prenatal diagnosis was provided for three couples through Sanger sequencing. Results All probands were found to carry pathogenic variants of the TMC1 gene, which included c.100C>T (p.R34X) and c.642+4A>C in family 1, c.582G>A (p.W194X) and c.589G>A (p.G197R) in family 2, c.1396_1398delAAC and c.1571T>C (p.F524S) in family 3, and homozygosity of c.2050G>C (p.D684H) in family 4. All parents were heterozygous carriers of the variants. The c.642+4A>C and c.1571T>C (p.F524S) were unreported previously. Prenatal diagnosis revealed that none of the fetuses were affected. Follow-up confirmed that all newborns had normal hearing. Conclusion Variant of the TMC1 gene probably underlay the deafness in the four families. Above findings have enhanced our understanding of the function of the TMC1 gene and enriched its variant spectrum. The results also facilitated genetic counseling and prenatal diagnosis for the families.