A growing number of studies have shown that the total loss of function of the USH2A protein predisposes patients to Usher syndrome type IIa but that remnant protein function can lead to RP with or without hearing loss, indicating that mutations in the USH2A gene are relatively less harmful in nonsyndromic RP than in Usher syndrome type IIa. The gene discussed is USH2A; the disease is retinitis pigmentosa 1.