Twelve novel myosin VIIA mutations in 34 patients with Usher syndrome typeI: Confirmation of genetic heterogeneity

Usher syndrome is a heterogeneous autosomal recessive trait and the most co mmon cause of hereditary deaf-blindness. Usher syndrome type I (USH1) is ch aracterised by profound congenital sensorineural hearing loss, vestibular d ysfunction, and prepubertal onset of retinitis pigmentosa. Of the at least six different loci for USH1, USH1B maps on chromosome 11q13, and the MYO7A gene has been shown to be defective in USH1B. MYO7A encodes myosin VIIA, an unconventional myosin, and it consists of 48 coding exons. In this study, MYO7A was analysed in 34 unrelated Usher type I patients by single-strand c onformation polymorphism analysis and direct sequencing. We identified a to tal of 12 novel and unique mutations, all single base changes. In addition, we found a previously reported nonsense mutation (C31X) on nine alleles of a total of six patients from Denmark. Hum Mutat 13:133-140, 1999. (C) 1999 Wiley-Liss, Inc.