Clinical Heterogeneity in a Family With Mutations in USH2A

Patients with Usher syndrome typically have progressive visual impairment due to retinitis pigmentosa (RP) and varying levels of deafness with or without vestibular involvement. Usher syndrome type 2 is the most common of the 3 clinical subtypes that have been described; it is associated with RP, moderate to severe congenital hearing impairment, and normal vestibular function. Autosomal recessive mutations in USH2A are the most common cause of Usher syndrome type 2.¹ Although a high degree of clinical heterogeneity has been described in USH2A-related disease, the ocular phenotype is usually concordant within families. Herein, we describe 2 siblings harboring the same USH2A mutations (c.[1036A>C];[13316C>T], p.[Asn346His];[Thr4439Ile]) with very different ocular and electrophysiological phenotypes.