Mutation scanning and direct DNA sequencing of all 50 exons of ABCR were completed for 150 families segregating recessive Stargardt disease (STGD1). ABCR variations were identified in 173 (57%) disease chromosomes, the majority of which represent missense amino acid substitutions. These ABCR variants were not found in 220 unaffected control individuals (440 chromosomes) but do cosegregate with the disease in these families with STGD1, and many occur in conserved functional domains. Missense amino acid substitutions located in the amino terminal one-third of the protein appear to be associated with earlier onset of the disease and may represent misfolding alleles. The two most common mutant alleles, G1961E and A1038V, each identified in 16 of 173 disease chromosomes, composed 18.5% of mutations identified. G1961E has been associated previously, at a statistically significant level in the heterozygous state, with age-related macular degeneration (AMD). Clinical evaluation of these 150 families with STGD1 revealed a high frequency of AMD in first- and second-degree relatives. These findings support the hypothesis that compound heterozygous ABCR mutations are responsible for STGD1 and that some heterozygous ABCR mutations may enhance susceptibility to AMD.
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Case#: Family AR321 proband, US, 6yo at onset
DiseaseAssertion: Stargardt
FamilyInfo: proband and two other siblings are affected
CasePresentingHPOs: The essential and defining features of STGD were (1) pedigrees with at least one living affected individual compatible with autosomal recessive inheritance; (2) an ophthalmoscopically characteristic retinal disorder in families with both parents living; (3) bilateral central visual loss with both “beaten metal” elliptical foveal dystrophy and temporal pallor of the optic discs, documented by retinal color photography, with or without yellow-pigment epithelial flecks in the macular and/or retinal “near periphery”; and (4) the characteristic fluorescein angiographic feature of a dark choroid (Blacharski 1988).
CaseHPOFreeText:
CaseNotHPOs:
CaseNotHPOFreeText: (1) evidence of autosomal dominant inheritance; (2) any history of night blindness, loss of peripheral vision, or "retinitis pigmentosa"; (3) cataracta complicata or cells in the vitreous; (4) substantially abnormal electroretinographic or electrooculographic responses; (5) no fluorescein angiography performed or no dark choroid documented; (6) neurological disease (including loss of cognition or seizures); 7) drug exposures (especially to antimalarial and agents known to cause crystalline retinopathies); or (8) any "atypical" maculopathies in which a unique diagnosis of STGD could not be established.
PreviouslyPublished: PMID: 8533764
Variant: c.3113C>T p.A1038V; c.1715G>C p.R572P . Heteroduplex and SSCP analyses were used to screen the 50 exons of ABCA4. Linkage analysis and haplotype analysis were previously performed
ClinVar: 99073
CAID: CA226919
SupplementalData: n/a