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Ada Orrico, Paolo Melillo, Valentina Di Iorio, Settimio Rossi, Michele Della Corte, Francesco Testa, Francesca Simonelli; Clinical and genetic study of late onset Stargardt disease. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2684. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To provide a detailed phenotype characterization of late onset Stargardt disease (STGD1) compared to the juvenile form.
We reviewed the medical charts of STGD1 patients, who underwent best-corrected visual acuity (BCVA), fundus photography, optical coherence tomography, full-field electroretinography, and microperimetry. Statistical analysis of onset age was done to identify a cut-off to discriminate between typical juvenile and late onset forms. Regression models were fitted in order to evaluate the disease progression. The study adhered to the tenets of the Declaration of Helsinki and received approval by the Local Ethics Committee.
The study cohort consisted of 205 patients with clinical diagnosis of STGD1 and mutations on both ABCA4 alleles. The onset age showed a bimodal distribution and the cut-off between typical juvenile and late-onset forms was estimated as 30 years. These findings led to the identification of a group of 56 patients with the typical juvenile onset (group A) and 20 patients with onset age over 30 years (group B), with at least one follow-up visit. The age of patients at baseline in group A ranged from 11 to 52 years (29.9±1.4 years), the onset age from 4 to 27 years (17.0±0.7 years) and disease duration from 1 to 46 (11.8±1.4 years). The age of patients at baseline in group B ranged from 38 to 71 years (48.2±1.9 years), the onset age from 32 to 48 years (38.5±1.1 years) and disease duration from 2 to 28 years (9.7±1.5 years). No significant differences (p>0.05) were observed in the Fishman and Lois class distribution. Disease progression was estimated in both groups, with reference to disease length. The BCVA decreased with a rate of 0.093 (p<0.001) and 0.019 (p=0.111) logMAR per year in group A and B, respectively. Both groups showed a significant decrease of MS (β=-0.028, p=0.001 in group A; β=-0.037, p=0.017 in group B), whereas the fixation stability significantly worsened in group A (β=-0.010, p=0.014), while appeared to be stable in group B (β=-0.007, p=0.302). Genetic analysis revealed that missense mutations (particularly G1961E) were more frequent in group B than group A.
The current study accurately describes a disease form characterized by a later onset, enabling to estimate its prevalence as 10% of STGD1 population. The late onset form was associated with a milder clinical phenotype and, genetically, more frequent missense mutations compared to typical juvenile STGD1.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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