['Canine X-linked progressive retinal atrophy (XLPRA) is a hereditary, progressive retinal degeneration that has been mapped previously to the canine X chromosome in a region flanked by the dystrophin (DMD) and tissue inhibitor of metalloproteinase 1 (TIMP1) genes, and is tightly linked to the gene RPGR. The comparable region of the human X chromosome includes the disease locus for RP3, an X-linked form of retinitis pigmentosa, although the current canine disease interval is much larger.', 'To refine the map of the canine XLPRA disease interval, 11 X-linked markers were mapped, both meiotically, in two extensive canine pedigrees informative for XLPRA, and on a 3000-rad canine-hamster radiation hybrid (RH) panel. A 12th marker was mapped on the RH panel alone.', 'The integrated map of this region of CFAX now covers approximately 47.3 centimorgans (cM) and 194 centirays (cR)(3000), and demonstrates strong conservation of synteny between humans and dogs. Genes defining the human RP3 zero-recombination interval (human homologue of mouse t complex [TCTE1L], sushi repeat-containing protein, X chromosome [SRPX], and retinitis pigmentosa guanosine triphosphatase [GTPase] regulator [RPGR]) are tightly linked to each other, to the XLPRA locus, and to the gene ornithine transcarbamylase (OTC) in dogs.'] Does fine mapping of canine XLPRA establish homology of the human and canine RP3 intervals?