Usher syndrome in four hard-of-hearing siblings.

Retinitis pigmentosa (RP) and congenital deafness comprise the autosomal recessive Usher syndrome. The four affected siblings discussed here have audiometric curves characteristic of the 10% of patients with the syndrome who are not profoundly deaf. The oldest already has RP. Even though the younger three siblings have no visual symptoms, they do have auditory signs of the syndrome; they almost certainly will develop RP and become deaf-blind adults. Electroretinography indicates that the second oldest boy has early evidence of rod dysfunction. Special audiometric tests and electronystagmographic results support previous reports of a peripheral rather than central auditory lesion. The heterozygote parents show unilateral high-frequency hearing losses with normal retinal and vestibular function.