It is a fact that both USH2 and non-syndromic RP are the most prevalent phenotypic variants of IRD caused by autosomal recessive USH2A variants, the findings of current investigation and previous one by Carss et al. [49] clearly demonstrate this fact and additionally, excluded the presence of a putative genetic modifier factor within the USH2A gene that may contribute in the development of two phenotypes. The gene discussed is USH2A; the disease is retinitis pigmentosa 1.