Linkage to this marker was not found in the USH1 families.Īt least 1 family studied by Pieke Dahl et al. In the USH2 kindreds, linkage was found to DNA marker THH33 located on 1q maximum lod score = 6.5 at 9 cM. (1990) performed linkage studies in 6 families with USH1 and 22 families with USH2. Nine USH1 families failed to show linkage to the same 3 markers. (1990) found linkage to 3 markers in the distal region of 1q, with a maximum multipoint lod score of 6.37 at marker THH33 (D1S81). In studies of 8 USH2 families, Kimberling et al. The foveal thickness ranged from 159 to 384 micrometers and was not correlated with retinal function. Optical coherence tomography (OCT) demonstrated loss of foveal depression with distortion of the foveal architecture in the macula of all patients. In all patients examined with ERG, the 30 Hz flicker response revealed remaining cone function. (2011) evaluated visual function, comprising both the severity of the rod cone degeneration and the function in the macular region, in 12 patients genotyped as Usher syndrome 1B, 1D, 1F, 2A, 2C, or 3A, including 3 families with affected sibs, and confirmed phenotypic heterogeneity between sibs with the same genotype and between patients with different genotypes. Their findings suggested the existence of stereotypical disease mechanism(s) that may characterize most patients with RP and related conditions once their degenerative process has become symptomatic. (2004) found that the kinetics of Goldmann visual field (GVF) decline in 19 patients with Usher syndrome type II were, on average, very similar to those in other forms of RP. In addition, the onset of RP was slightly later in type IIb, occurring in the late second or early third decade. The hearing loss in type IIa was greater than that in type IIb at low frequencies (0.25, 0.5, and 1 kHz). (2002) compared the findings in this family with those in a family with Usher syndrome type IIb. Mutation analysis detected a mutation in the usherin gene that segregated with the disorder. Audiometry tests showed a moderate to profound bilateral sensorineural hearing loss, and ophthalmologic examination detected RP with the appearance of night blindness in the first or second decade. (2002) reported a family from Tunisia in which 7 members were affected with Usher syndrome type IIa. (1997) concluded that sperm of patients with RP, particularly those with Usher syndrome type II, may have an abnormal lipid composition that is associated with reduced motility. Lower erythrocyte DHA was also observed in RP patients. Sperm DHA concentration was positively correlated to sperm motility, to sperm count, and to the desmosterol-to-cholesterol ratio. Patients with Usher syndrome type II exhibited the most pronounced reductions of DHA in sperm. The sperm of patients with RP had a much lower DHA concentration, a lower desmosterol-to-cholesterol ratio, reduced motility, abnormal structure, and lower sperm counts compared with that in normal subjects. (1997) studied the lipid composition of erythrocytes and sperm in 26 patients with RP and in 8 healthy men. Thus, the DNA-damaging effects of chemotherapy may have had particularly deleterious consequences for this patient.īased on the observation that both sperm and retina are rich in docosahexaenoic acid (DHA) and that blood levels of DHA in RP patients are less than normal, Connor et al. Lymphoblastoid cells from dominantly inherited RP showed no hypersensitivity. (1984) claimed that lymphoid and fibroblast cell lines derived from patients with Usher syndrome are hypersensitive to DNA-damaging agents such as x-ray. (1992) described a patient with presumably type II Usher syndrome who had apparent acceleration of retinitis pigmentosa following cytotoxic chemotherapy for non-Hodgkin lymphoma. (1998) characterized type IIa Usher syndrome as showing moderate to severe sensorineural hearing loss as well as progressive retinitis pigmentosa.īlanchet et al. Usher syndrome, type IIC, GPR98/PDZD7 digenicĮudy et al. Usher syndrome, type 2C, GPR98/PDZD7 digenic
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