Case Report of a Child with High Myopia and Night Blindness Combined with Mutations of the ABCA4, USH2A, and NYX Genes

Background: High myopia (HM) is a hereditary disease affected by multiple genes. Increasingly, more genes related to HM are being discovered. Among them, the ABCA4 and USH2A genes have been included in the ClinVar database as candidate genes for HM; However, they have not been reported in the literature, and there is a lack of clinical evidence for their inclusion in the database. The NYX gene, as a pathogenic gene of night blindness, also still lacks clinical case reports to support its influence in this context.Case Report: The case presented herein concerns a 2-year-old boy whose 14-year-old brother had been diagnosed with HM by optometric testing at 4-years of age. The patient's parents had no history of HM and thus took their child to the Shenzhen Eye Hospital for an examination; He was eventually diagnosed with HM and night blindness. Gene sequencing detected heterozygous mutations in the ABCA4 and USH2A genes and a homozygous mutation in the NYX gene (hemizygote; The hemizygote here and later refers to the XYX gene of this patient).Conclusions: This case report provided clinical evidence for the ABCA4 and USH2A genes as pathogenic genetic material for HM and found a new site of NYX gene (c. 199_200insTCGACC) for night blindness.