Mutations in retinol dehydrogenase 12 (RDH12) cause severe retinal degeneration. However, some of the disease-associated RDH12 mutants retain significant catalytic activity, indicating the existence of additional pathophysiological mechanisms. This study demonstrates that the catalytically active T49M and I51N mutants undergo accelerated degradation, which results in their reduced cellular levels. Inhibition of proteasome leads to significant accumulation of ubiquitylated T49M and I51N. Furthermore, the degree of ubiquitylation strongly correlates with the half-lives of the proteins. These results suggest that the accelerated degradation of RDH12 mutants by the ubiquitin-proteasome system contributes to the pathophysiology and phenotypic variability associated with mutations in the RDH12 gene. Structured summary: MINT-7383581, MINT-7383598: RDH12 (uniprotkb:Q96NR8) physically interacts (MI:0915) with ubiquitin (uniprotkb:P62988) by anti tag coimmunoprecipitation (MI:0007). © 2009 Federation of European Biochemical Societies.