The first USH2A mutation analysis of Japanese autosomal recessive retinitis pigmentosa patients: a totally different mutation profile with the lack of frequent mutations found in Caucasian patients.

Retinitis pigmentosa (RP) is a highly heterogeneous genetic disease. The USH2A gene, which accounts for approximately 74-90% of Usher syndrome type 2 (USH2) cases, is also one of the major autosomal recessive RP (arRP) causative genes among Caucasian populations. To identify disease-causing USH2A gene mutations in Japanese RP patients, all 73 exons were screened for mutations by direct sequencing. In total, 100 unrelated Japanese RP patients with no systemic manifestations were identified, excluding families with obvious autosomal dominant inheritance. Of these 100 patients, 82 were included in this present study after 18 RP patients with very likely pathogenic EYS (eyes shut homolog) mutations were excluded. The mutation analysis of the USH2A revealed five very likely pathogenic mutations in four patients. A patient had only one very likely pathogenic mutation and the others had two of them. Caucasian frequent mutations p.C759F in arRP and p.E767fs in USH2 were not found. All the four patients exhibited typical clinical features of RP. The observed prevalence of USH2A gene mutations was approximately 4% among Japanese arRP patients, and the profile of the USH2A gene mutations differed largely between Japanese patients and previously reported Caucasian populations.

Visual Outcomes in Japanese Patients with Retinitis Pigmentosa and Usher Syndrome Caused by USH2A Mutations.

PURPOSE: EYS and USH2A are the most common causative genes for retinitis pigmentosa (RP) in Japan. We determined the clinical outcomes for USH2A-related non-syndromic RP or Usher syndrome type II (USH2). METHODS: Two non-syndromic RP and 11 USH2 patients with previously identified USH2A mutations were included. Their complete history and medical records were collected using standard procedures. Visual fields and acuity were compared with those of patients with EYS mutations. Clinical analyses were based on ophthalmic and otolaryngologic examinations. RESULTS: In all patients, the fundus displayed changes typical of RP. Most patients showed relatively well-preserved visual acuity in their thirties or forties, with rapid deterioration in their fifties. Concentric constriction started in the twenties or thirties, and no effective residual visual field was observed after the fifties. CONCLUSIONS: The visual outcome for non-syndromic RP or USH2 patients with USH2A mutations is consistent with that for RP patients with EYS mutations.

Novel OPN1LW/OPN1MW deletion mutations in 2 Japanese families with blue cone monochromacy.

Blue cone monochromacy (BCM) is caused by the lack of expression of the normal proteins encoded by the OPN1LW and OPN1MW genes, resulting in the absence of red and green cone sensitivities. We analyzed two cases of BCM in two different families and identified deletion mutations in the locus control region upstream of the two genes. Deletion breakpoints were determined to an accuracy of one base for both cases.

Clinical phenotype in ten unrelated Japanese patients with mutations in the EYS gene.

BACKGROUND: To characterize the clinical phenotypes associated with previously-reported mutations of the eyes shut homolog (EYS) gene, including a truncating mutation, c.4957_4958insA, which is a major causative mutation for retinitis pigmentosa (RP) in Japan. MATERIALS AND METHODS: The study population comprised ten unrelated RP subjects with very likely pathogenic mutations in both alleles, four of them with a homozygous c.4957_4958insA mutation. The phenotype analysis was based on ophthalmic examination, Goldmann perimetry, and digital fundus photography. RESULTS: The study population included six men and four women aged 34-74 years. The average age at first visit was 31 years (range, 14-44 years), and the patients typically presented with night blindness as the initial symptom and subsequently developed progressive constriction of the visual field. Myopia was noted in 9/20 affected eyes. For most patients, central visual acuity was preserved relatively well up to their thirties, after which it deteriorated rapidly over the next two decades. The visual acuity of patients homozygous for the c.4957_4958insA mutation was uniform. Visual fields were constricted symmetrically, and the extent of constriction seemed to be better correlated with age than visual acuity. The fundus displayed bone spicules, which increased in density with age, and attenuated retinal vessels. CONCLUSIONS: Although additional studies with more patients with mutations of the EYS gene are required, it appears that patients share a relatively uniform phenotype with near-normal central visual function up to their twenties. The patients homozygous for the c.4957_4958insA mutation showed a uniform course of visual acuity changes.