5, 6 USH2A encodes for usherin, a basement membrane protein in the inner ear and retina, 7 and is expressed in additional tissues as well. 4Īt least 3 genetic USH2 loci were identified with USH2A being the most common, responsible for approximately 85% of USH2cases. 2, 3 Usher type 3 is found mostly among Finnish patients with onset of progressive hearing loss and RP in the late teens and variable vestibular dysfunction. 1 Usher syndrome can be categorized into 3 clinical types: patients with Usher type 1 (USH1)typically have congenital deafness, vestibular ataxia, and night blindness noted in the first or second decade, whereas in USH2, night blindness appears in the second to fourth decade, accompanied by moderate early-onset hearing loss and no ataxia. Most patients have no associated systemic disease (nonsyndromic RP) while others suffer from associated extraocular diseases.The most common syndromic RP is Usher syndrome, with an estimated prevalence of 5:100 000 live births. Retinitis pigmentosa (RP) is a group of progressive rod-cone degenerations characterized by night blindness followed by visual-field loss, resulting in severe visual impairment. Compound heterozygotes for 2 null mutations (Thr80fs and Arg737stop) in MOL0051 suffered from USH2 while compound heterozygotes for 1 of the null mutations and a novel missense mutation (Gly4674Arg) had nonsyndromic RP.Ĭonclusions Our results support the involvement of USH2A in nonsyndromic RP and we report here of a second, novel, missense mutation in this gene causing autosomal-recessive RP.Ĭlinical Relevance Possible involvement of USH2A should be considered in the molecular genetic evaluation of patients with autosomal-recessive RP.Understanding the mechanism by which different USH2A mutations cause either USH2 or RP may assist in the development of novel therapeutic approaches. Results The analysis revealed 3 USH2A mutations, 2of which are novel, in 2 families with USH2 and a large family (MOL0051) with both USH2 and RP. The frequency of novel missense changes was determined in patients and controls using restriction endonucleases. USH2A exons 2-72 were scanned for mutations using single-strand conformation and sequencing analyses. Methods Patients from 95 families with RP and 4 with USH2 were clinically evaluated. Objective To identify USH2A mutations in Israeli patients with autosomal-recessive Usher syndrome type 2 (USH2) and retinitis pigmentosa (RP). Shared Decision Making and Communication.Scientific Discovery and the Future of Medicine.Health Care Economics, Insurance, Payment.
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