_:vb50942979 . _:vb50942979 . _:vb50942979 . _:vb50942979 "url:https://www.ncbi.nlm.nih.gov/pubmed/8394174"^^ . _:vb50942979 . _:vb50942979 . _:vb50942979 "A retinitis pigmentosa that has_material_basis_in mutation in the PDE6B gene on chromosome 4p16."^^ .