The ablation of ROM1 leads to a change from the macular/pattern dystrophy (MD/PD) phenotype characterized by a defect in cone function to a retinitis pigmentosa (RP) phenotype characterized by a dominant defect in rod function, and the formation of abnormal Prph2/ROM1 complex and total Prph2 protein decreased. The gene discussed is PRPH2; the disease is retinitis pigmentosa.