In order to gain new insights into the pathogenesis of ARRP, we evaluated the morphological, biochemical, and gene expression changes in eyes from a human donor with ARRP due to mutations in the ABCA4 gene.
Mutations in ABCA4 have been associated with autosomal recessive Stargardt disease, autosomal recessive cone-rod dystrophy, and autosomal recessive retinitis pigmentosa.
Mutations in ABCA4 have been associated with autosomal recessive Stargardt disease (STGD), a few cases with autosomal recessive cone-rod dystrophy (arCRD) and autosomal recessive retinitis pigmentosa (arRP).
However, his affected sister, who had the arRP phenotype, was found to be heterozygous for this allele; no other sequence change could be found in ABCA4.
Among the 500 ABCA4 mutations identified so far in the retina-specific ABC transporter (ABCA4) gene, only 20 have been described in patients with autosomal recessive retinitis pigmentosa (arRP).
Our results revealed the presence of three novel mutations: c.160T>G (p.C54G), c.2486C>T (p.T829M), and c.973-6C>A; two mutations previously reported, c.634C>T (p.R212C) and c.4253+4C>T, and several polymorphic changes in the ABCA4 gene among Turkish patients affected with Stargardt and arRP.
Several reports have shown that mutations in the ABCR gene can lead to Stargardt disease (STGD)/fundus flavimaculatus (FFM), autosomal recessive retinitis pigmentosa (arRP), and autosomal recessive cone-rod dystrophy (arCRD).
However, a gene for autosomal recessive retinitis pigmentosa with distinctive features of choriocapillaris atrophy at an advanced stage (RP19) has been mapped to the genetic interval encompassing the STGD gene on chromosome 1p (D1S435-D1S236), raising the question of whether, despite striking differences in clinical course and presentation, RP19 and STGD might be allelic disorders at the ABCR locus.