While this study provides robust insights into genotype-phenotype correlations in late-onset STGD1 and severe STGD1 cases, further investigation into underlying mechanisms of photoreceptor mislocalisation, altered stress-signalling pathways, inclusion of more diverse STDG1 cases and more congruent RO differentiation methods over longer time points would significantly enhance our understanding of the spectrum of ABCA4-associated pathology. This evidence concerns the gene ABCA4 and severe early-childhood-onset retinal dystrophy.