The genetic diagnosis was made before onset of RP in 10 young patients with apparently isolated hearing impairment: nine with Usher syndrome due to mutations in MYO7A and USH2A, and one with a peroxisome biogenesis disorder (PBD) due to compound heterozygous PEX26 mutations. The gene discussed is MYO7A; the disease is Peroxisome biogenesis disorder-Zellweger syndrome spectrum.