Usher Syndrome, Type III (CLRN1)
Usher syndrome type 3 is an autosomal recessive disease caused by pathogenic variants in the gene CLRN1. While it is a pan-ethnic disease, due to the presence of a founder mutation it is found more frequently in individuals of Ashkenazi Jewish descent. The disease is characterized by postlingual hearing loss and retinitis pigmentosa of varying severity, which usually begins in adolescence. Retinitis pigmentosa first presents with night blindness, but progresses to tunnel vision and loss of visual acuity. Some patients with mild missense variants may develop retinitis pigmentosa only, without exhibiting hearing loss.
For information about carrier frequency and residual risk, please see the residual risk table.