Historically from<unk> ’s first description of his eponymous disease until recently, the diagnosis was based on looking at the phenotype using examination and investigation of the eye. Since the advent of genetic testing, the picture has become more complex. What was thought to be one disease is, in fact, probably at least three different diseases, each related to a different genetic change. Therefore it is currently a little confusing to define what<unk> 's disease is.<unk>  <unk> 1) is caused by bi-allelic ABCA4 gene variants (i.e., autosomal recessive). Importantly, the exact genotype (i.e., combinations of both ABCA4 variants) is highly prognostic for the age of onset and disease progression. Autosomal-dominant<unk> -like diseases were linked to genes such as PROM1 <unk> 3) or ELOVL4 <unk> 4) missense mutations play a role remains to be seen. The carrier frequency in the general population of ABCA4 alleles is 5 to 10%. Different combinations of ABCA4 genes will result in widely different age of onset and retinal pathology. The severity of the disease is inversely proportional to ABCA4 function and it is thought that ABCA4 related disease has a role to play in other diseases such as retinitis pigmentosa, cone-rod dystrophies and age-related macular degeneration (AMD). *<unk> 1: By far the most common form of<unk>  is the recessive form caused by mutations in the ABCA4 gene. *<unk> 4: A rare dominant defect in the PROM1 gene. *<unk> 3: A rare dominant form of<unk>  caused by mutations in the ELOVL4 gene. * Late-onset<unk>  is associated with missense mutations outside known functional domains of ABCA4.
Stargardt disease
Akureyri disease
Pickardt syndrome
Batten disease
Keshan disease
Lafora disease
Thiel–Behnke dystrophy
Bosch-Boonstra-Schaaf optic atrophy syndrome