Usher Syndrome, Type IIA (USH2A)
Usher syndrome type 2A is an autosomal recessive disease caused by pathogenic variants in the gene USH2A. While it is a pan-ethnic disease, due to the presence of a founder mutation it is found more frequently in Sephardic Jewish individuals from Iraq and Iran. The disease is characterized by congenital moderate to severe hearing loss, and patients may benefit from the use of hearing aids. Progressive loss of vision due to retinitis pigmentosa begins in late childhood or adolescence. Retinitis pigmentosa first presents with night blindness, but progresses to tunnel vision and eventually blindness. Several specific variants have been associated with a milder form of the disease, and therefore disease severity may be predicted in some patients.
For information about carrier frequency and residual risk, please see the residual risk table.