This group of disorders may be caused by mutations in at least 4 genes. These are: STGD1 (248200) caused by mutations in the ABCA4 gene located at 1p22.1, or in CNGB3 (262300) (8q21-q22) which also is mutant in achromatopsia 3 (ACHM3), STGD3 (605512) caused by mutations in the ELOVL4 gene at 6q14, and STGD4 (603786) caused by a mutation in PROM1 on chromosome 4p. STGD4 and STGD3 disease have been found in pedigrees consistent with autosomal dominant inheritance but STGD1 disease seems to be inherited in an autosomal recessive pattern.
Genotyping is necessary for accurate diagnostic determinations. In particular, a few patients clinically found to have typical areolar macular dystrophy, retinitis pigmentosa, juvenile macular degeneration, and cone dystrophies have been reported in association with several of these mutations and reports have also associated Stargardt disease with mutations in RDS.
A single family with a brother and sister with Stargardt disease and neurological malformations has been reported (612948). Both had developmental delays associated with absence or hypoplasia of the corpus callosum, upslanted lid fissures, 'flared eyebrows', a broad nasal tip, a broad face with a pointed chin, and sensorineural hearing loss along with mild digital malformations. Evidence of macular degeneration was seen at age 7 years and vision in both individuals was in the 20/100-20/200 range. No associated locus or mutation has been identified.