ABCA4 and severe early-childhood-onset retinal dystrophy: The vast majority of ABCA4 positive cases (n = 501 [93.7%]) had a diagnosis of STGD1 (n = 470), CD/CRD (n = 28), pattern dystrophy (n = 2) or ACHM (n = 1), in line with the strong association of biallelic ABCA4 mutations with cone-dominated phenotypes that primarily affect the central retina.