Novel compound heterozygous mutations in MYO7A in a Chinese family with Usher syndrome type 1

Usher syndrome (USH) is an autosomal recessive disease characterized by the association of retinitis pigmentosa (RP) and sensorineural hearing loss (SNHL), with or without vestibular dysfunction. The syndrome is the most common cause of combined blindness and deafness, accounting for more than 50% of individuals who are both deaf and blind, about 18% of RP cases, and 5% of all cases of congenital deafness [ 1]. According to previous reports, the overall preva -lence of USH ranges from 3.2 per 100,000 to 6.2 per 100,000 individuals [2].Clinically, USH is divided into three types based on disease severity and progression of the clinical course. Usher type 1 (USH1) is characterized by profound congenital deafness, vestibular areflexia, and early onset RP. Patients with type 2 (USH2) display moderate to severe hearing loss and later onset of RP. Patients with Usher syndrome type 3 (USH3) show progressive postlingual hearing loss, variable onset of RP, and variable vestibular dysfunction. Genetically, Usher syndrome is highly heterogeneous. To date, mutations in 12 loci and ten genes have been found to be responsible for USH. For USH1, six genes—