Based on limited published evidence, RPEL1 catalyzes the reversible epimerization of D-ribulose 5-phosphate to D-xylulose 5-phosphate, functioning in the non-oxidative pentose-phosphate pathway. The protein localizes to the cytosol and contains metal ion binding activity. RPEL1 gene polymorphisms (rs4917385) have been associated with susceptibility to systemic lupus erythematosus and anxiety symptoms in Chinese populations 1. RPEL1 was investigated as a candidate gene for autosomal dominant hearing impairment but no disease-causing mutations were identified 2.