Gieser et al. (1998) described a 5-generation family with X-linked retinitis pigmentosa designated RP24. Affected males (hemizygotes) had early onset of rod photoreceptor dysfunction; cone-receptor function was normal at first, but there was progressive loss. Patients at advanced ... Gieser et al. (1998) described a 5-generation family with X-linked retinitis pigmentosa designated RP24. Affected males (hemizygotes) had early onset of rod photoreceptor dysfunction; cone-receptor function was normal at first, but there was progressive loss. Patients at advanced stages showed little or no detectable rod or cone function and had clinical hallmarks of typical RP.