We report the cloning of a novel human cDNA which encodes a 690 amino acid protein with high homology to ubiquitin C-terminal hydrolases. Northern blot analysis shows expression of a 3.3 kb transcript in all tissues examined, with 5- to 10-fold higher levels in retina than elsewhere. We mapped the structural gene to Xp21.2-p11.2. This gene's relatively high levels of retinal expression and recent work showing that perturbations in protein turnover and processing can lead to retinal disease make it an excellent candidate for several X-linked retinal disorders mapping within this interval. Additionally, there is evidence that members of the ubiquitin hydrolase family may play a role in oncogenesis and a locus implicated in ovarian cancer is also located within this region.