CRB1 and respiratory distress syndrome in premature infants: Although limited genotype–phenotype correlations have been found for CRB1-linked IRDs, other than the association of the in-frame deletion p.(Ile167_Gly169) with a restricted macular dystrophy phenotype, null variants are associated with greater disease severity, and this is perhaps explained by a disruption of all CRB1 isoforms.17