In 2007, a female with a clinical diagnosis of STGD was demonstrated to carry a homozygous c.3386G>T (p. Arg1129Leu) pathogenic variant in ABCA4, and analysis of microsatellite markers along the entire chromosome 1 showed that the isodisomy spanned a 4.4-Mb segment that included the ABCA4 gene (Riveiro-Alvarez et al., 2007). Here, ABCA4 is linked to severe early-childhood-onset retinal dystrophy.