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Rafael Purissimo, Marcos P Avila, John Chiang, Leticia Dourado Alves, Luiz G Freitas, Ricardo C Cruvinel, Claudia Sousa, Carolina B Paiva, Rafael Yamamoto, Luis Alexandre Rassi Gabriel; Identification of 4 novel mutations in the ABCA4 gene in brazilian patients with Stargardt disease type I. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3254.
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© ARVO (1962-2015); The Authors (2016-present)
To present 4 novel mutations (3 frameshift and 1 missense) in the ABCA4 gene identified in brazilian patients with typical Stargardt disease type I.
Ophthalmic examination was performed. Best corrected visual acuity (BCVA) was done with the Snellen chart. Retinography, (TRC50DX Topcon) and spectralis optical coherence tomography-OCT (Heidelberg Engineering Inc) were performed. Direct testing for mutations in the ABCA4 gene was performed by PCR amplification and bidirectional DNA sequencing of all coding exons and exon/intron boundaries in a CLIA certified laboratory. The results were analyzed and compared to the NCBI reference sequence NM_000350.2. The bioinformatic tools Polyphen-2 and Mutation Taster were used to predict the effect of the missense mutation on the protein.
BCVA range was from 20/100 to 20/800 in all patients. Retinography revealed typical macular beaten-bronze appearence, flecks in the younger patients, and dark choroid sign in all cases. The OCT showed a decreased foveal thickness on three patients. The ABCA4 sequencing identified the following novel mutations: homozygous c.2007G>C:p.M669I; heterozygous c.180_delG; heterozygous c.2782insG; and homozygous c.6471_delC. The novel missense mutation was predicted as disease causing by Polyphen-2 and Mutation Taster.
Herein we’ve described 4 novel mutations in ABCA4 in brazilian patients with Stargardt disease, suggesting the existence of a different ABCA4 mutation prevalence in Brazil.
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