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Mariana Vallim Salles, Karita A Costa, Fabiana L Motta, Elton D Silva, Patricia V Teixeira, Joao Bosco Pesquero, Juliana M F Sallum; ABCA4 gene screening by next-generation sequencing in Brazilian Stargardt patients. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1424.
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Identify ABCA4 gene mutations in patients with clinical diagnosis of Stargardt disease.
Select patients with clinical diagnosis of Stargardt disease. The age of onset and visual acuity was registered. To characterize their phenotypic characteristics, the Fundus photography, OCT and fundus autofluorescence were recorded. Patients were classified into three fundus autofluorescence subtypes: type 1 had a localized low autofluorescence signal at the fovea surrounded by a homogeneous background; type 2 had a localized low signal at the macula surrounded by a heterogeneous background with numerous foci of abnormal signal; type 3 had multiple low signal areas at the posterior pole with a heterogeneous background. DNA was extracted from the periferal blood. The ABCA4 gene has been sequenced by next generation sequencing technique to search for variations that could be potentially related to Stargardt disease.
Twenty three patients from 20 families (3 pair of siblings), all of them between 10 and 66 years old, were included. In this population the median age of onset was 13 years old (range, 6-30years). The patients visual acuity ranged from 20/40 to count fingers at 50 centimeters. The retina exam showed Stargardt macular dystrophy and hypoautofluorescence at the atrophic areas and hyperautofluorescent at fleck lesions. According to the AF classification, 3 patients showed a mild phenotype at autofluorescence exame (type 1), 11 with moderate aspect (type 2) and 10 with severe phenotype (type 3). The OCT showed outer retinal attenuation or loss at the central macula. The Next Generation Sequencing tests reveled 28 variants of which 20 were classified as disease-causing, including 17 missense, 2 nonsense (p.Arg1300*, p.Glu1574*) and 1 nonframeshift deletion (c.5044_5058del15).
The phenotype characteristics of all 23 patients are related to Stargardt disease. In 20 patients at least 2 disease-causing mutations were confirmed. The NGS technique was useful as screening method to search for mutations in the ABCA4 gene in Stargardt patients.
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