Novel TRPM1 mutations in two Chinese families with early-onset high myopia, with or without complete congenital stationary night blindness.

AIM: To investigate the relationship between high myopia [with or without complete congenital stationary night blindness (CSNB1)] and TRPM1 and NYX.
METHODS: Two unrelated families with early-onset high myopia (eoHM) and 96 normal controls were recruited. Sanger sequencing or clone sequencing were used for mutation screening. Further analyses of the available family members and the 96 normal controls were subsequently conducted to obtain additional evidence of the pathogenicity of these variants. The initial diagnosis of the probands was eoHM. We performed a further comprehensive examination of the available family members after mutations were detected in TRPM1 or NYX.
RESULTS: Two novel compound heterozygous mutations in TRPM1 were detected in the recruited families. The proband in family A with eoHM carried a c.2594C>T missense mutation in exon 19 and a c.669+3_669+6delAAGT splicing mutation, which was co-segregated with CSNB1 in this family. A patient in family B with a compound heterozygous missense mutation (c.3262G>A and c.3250T>C) was detected. No mutations were found in NYX. These two identified compound heterozygous mutations were not found in the 96 normal controls. After further examination of the family members, the patients in family A could be diagnosed as eoHM with CSNB1. However due to the limited clinic data, the patient in family B cloud not clearly diagnosed as CSNB1.
CONCLUSION: This study has expanded the mutation spectrum of TRPM1 for CSNB1 and additional studies are needed to elucidate the association between isolated high myopia and TRPM1 and NYX.