Usher Syndrome, Type ID (CDH23)
Usher syndrome type 1D is an autosomal recessive, pan-ethnic disease caused by pathogenic variants in the gene CDH23. The disease is characterized by congenital bilateral sensorineural deafness, which may be treated by cochlear implants; hearing aids do not help. Progressive loss of vision due to retinitis pigmentosa begins in childhood. Retinitis pigmentosa first presents with night blindness, but progresses to tunnel vision and eventually blindness. Patients also have problems with their balance and therefore experience developmental delay. Some patients with missense variants, rather than null variants, may manifest only with deafness; however, it is not currently possible to predict a patients phenotype based on genotype. Life expectancy is not reduced.
For information about carrier frequency and residual risk, please see the Expanded Carrier Screen brochure.