Single-copy variants of the Stargardt disease gene ABCR have been shown to confer enhanced susceptibility to ARMD. Bernstein et al. (2002) examined 19 of 33 sibs from 15 Stargardt families who carried their respective proband's variant ABCR allele. ... Single-copy variants of the Stargardt disease gene ABCR have been shown to confer enhanced susceptibility to ARMD. Bernstein et al. (2002) examined 19 of 33 sibs from 15 Stargardt families who carried their respective proband's variant ABCR allele. Some families exhibited concordance of ABCR alleles with the macular degeneration phenotype, but others did not. Exudative ARMD was uncommon among both probands and sibs.
In 26 of 167 unrelated patients with age-related macular degeneration, Allikmets et al. (1997) identified mutations in the photoreceptor-specific gene ABCR (601691), which is also mutated in Stargardt disease (248200). They found a total of 13 different mutation, ... In 26 of 167 unrelated patients with age-related macular degeneration, Allikmets et al. (1997) identified mutations in the photoreceptor-specific gene ABCR (601691), which is also mutated in Stargardt disease (248200). They found a total of 13 different mutation, both deletions and amino acid substitutions, in heterozygous state (e.g., 601691.0006). They suggested that the identification of ABCR alterations will permit presymptomatic testing of high-risk individuals and may lead to earlier diagnosis of ARMD and new strategies for prevention and therapy. De La Paz et al. (1999) screened their patients with ARMD (159 familial cases from 112 multiple families and 53 sporadic cases) and 56 racially matched individuals with no known history of ARMD for evidence of mutation in the ABCR gene. The authors identified only 2 of the previously reported variants in their study population. Both variants occurred in sporadic cases, and none was found in familial cases or in the randomly selected population. In addition, the authors identified several previously undescribed polymorphisms and variants in both the ARMD and control populations. The authors concluded that mutation in the ABCR gene is not a major genetic risk factor for ARMD in their study population. Shroyer et al. (1999) analyzed the ABCA4 gene in a 3-generation family manifesting both Stargardt disease and ARMD, and identified heterozygosity for a missense mutation (P1380L; 601691.0026) in the paternal grandmother with ARMD, whereas the proband and his 2 paternal cousins with Stargardt disease were compound heterozygous for the P1380L mutation and another missense mutation (601691.0036 and 601691.0037, respectively) in the ABCA4 gene. Shroyer et al. (1999) suggested that carrier relatives of STGD patients may have an increased risk of developing ARMD.