_:vb50942994 . _:vb50942994 . _:vb50942994 . _:vb50942994 "A retinitis pigmentosa that has_material_basis_in mutation in the PRPH2 gene on chromosome 6p21."^^ . _:vb50942994 . _:vb50942994 "url:https://www.ncbi.nlm.nih.gov/pubmed/1749427"^^ . _:vb50942994 .