ii) Variant type, the severity of the phenotype appears to depend on the variant type of the mutant protein, as similar phenotype generated by another TULPs family member, TULP1. In TULP1, RP complicated with Leber congenital amaurosis (LCA) phenotypes were generally induced by splice-site or protein-truncating mutations distributed throughout the gene (Additional file 1: Fig. S3-B), whereas simple RP phenotype was always associated with pathogenic missense mutations located in the tubby domain of TULP1 (Additional file 1: Fig. S3-A). This evidence concerns the gene TULP1 and Leber congenital amaurosis.