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Ruifang Sui, Lizhu Yang, Xuan Zou, Huajin Li, Fangtian Dong; Phenotype and Genotype Characterization of a small cohort of Chinese patients with Occult Macular Dystrophy. Invest. Ophthalmol. Vis. Sci. 2017;58(8):581.
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© ARVO (1962-2015); The Authors (2016-present)
Occult Macular Dystrophy (OMD) is an inherited progressive ocular disease, featured by normal appeared fundus without clear functional impairment of the retina. Retinitis pigmentosa 1 like 1 gene (RP1L1) is the only confirmed gene related to OMD. This study aims to investigate the clinical characteristics of OMD and genetic changes in RP1L1 for a small cohort of Chinese patients.
Thirteen patients from 10 unrelated families with clinically diagnosed OMD were recruited. Ophthalmologic examinations including optic coherence tomography (OCT), visual field, full-field electroretinogram (ERG), pattern ERG (pERG) and multifocal ERG (mfERG) were performed. Sanger sequencing of RP1L1 were utilized to identify the pathogenic variants. Co-segregation analysis was performed to further confirm the causative variants.
There were 3 pedigrees with autosomal dominant (AD) inheritance and 7 sporadic cases. Twelve patients were bilaterally affected and one case was unilateral. The best corrected visual acuity (BCVA) among ranged from 0.02 to 1.0 with the median 0.2. The median onset age was 17 years with a range from 5 to 45 years. All patients appeared with normal fundus and localized dysfunction of the macular detected by electrophysiological examinations. Two RP1L1 mutations was identified in 3 families (3/10, 33.3%), including the hot-spot variant p. R45W identified in two AD pedigrees, and a novel variant p. R397X localized in an isolated patient. There are characteristic phenotype differences in OCT manifestation between RP1L1 positive group and negative group: all positive cases showed classical OCT manifestations with both blurred ellipsoid zone (EZ) and absence of interdigitation zone (IZ). While the RP1L1 negative group lacked at least one of these two features, which is defined as nonclassical OCT type.
This is the first study of genotype and phenotype features based on Chinese patient cohort. Our study identified one novel RP1L1 mutation (p. R397X) and confirmed that the hot spot pathogenic variants is associated with OMD in Chinese population. The microstructural difference between RP1L1 positive and negative groups indicates the possible genotype-phenotype correlation of OMD.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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