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Eva Lenassi, Zubin Saihan, Polona Le Quesne, Linda M. Luxon, Karen P. Steel, Maria Bitner-Glindzicz, Andrew R. Webster; Natural History and Retinal Structure in Patients with Usher Syndrome Type 1 Due to MYO7A Mutation. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4543.
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To report the clinical histories and fundus autofluorescence (FAF) in MYO7A-related disease. Mutations in the MYO7A gene are the most common cause of Usher syndrome type 1 featuring profound congenital deafness and progressive retinal degeneration.
Thirty-two patients from 30 families (age range 3 to 61; median 33 years) previously identified to harbor likely disease-causing variants in MYO7A (National Collaborative Usher Study; 176 families tested, 47/176 had Usher syndrome type 1) were studied. Clinical investigations included a detailed clinical history, fundus photography, spectral domain optical coherence tomography, fundus autofluorescence imaging, and audiological and vestibular assessment. Longitudinal visual acuity and FAF data (over a 5 year period) were available for 18 and 9 study subjects, respectively.
All individuals with MYO7A mutations presented with features consistent with Usher type 1. Median visual acuity for the cohort was 0.3 logMAR (range 0.0 to 2.2) and visual acuity in logMAR correlated with age (Spearman's correlation coefficient r = 0.65; P < 0.0001). Survival analysis revealed that acuity of ≤ 0.22 logMAR is maintained in 50% of studied subjects till age 43. Two distinct patterns were observed on fundus autofluorescence imaging: 16 of 26 patients tested had relatively preserved foveal autofluorescence surrounded by a ring of high-density; the remaining 10 had an abnormal foveal autofluorescent signal. Statistically significant differences in both age (P = 0.0002) and visual acuity (P < 0.0001) were identified between these two groups. Twenty-nine patients had proven or presumed biallelic variants in MYO7A and, overall, 41 likely disease-causing sequence alterations were identified. Despite a number of cases presenting with a significantly milder phenotype, there appeared to be no obvious genotype-phenotype correlation.
MYO7A-related disease is variable. Central vision typically remains preserved at least until the 4th decade of life. Fundus autofluoresence imaging is a clinically useful test in patients with Usher syndrome type 1. Further analysis of longitudinal data will provide important insights into disease progression.
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