Mondo Description Ribose-5-P isomerase deficiency is an extremely rare, hereditary, disorder of pentose phosphate metabolism characterized by progressive leukoencephalopathy and a highly increased ribitol and D-arabitol levels in the brain and body fluids. Clinical presentation includes psychomotor delay, epilepsy, and childhood-onset slow neurological regression with ataxia, spasticity, optic atrophy and sensorimotor neuropathy.

Uniprot Description A patient has been described with a deficiency of ribose 5-phosphate isomerase who presented with leukoencephalopathy and peripheral neuropathy. Proton magnetic resonance spectroscopy of the brain revealed a highly elevated level of the polyols ribitol and D-arabitol, which were subsequently also found in high concentrations in body fluids. Deficient activity of RPIA, one of the pentose phosphate pathway enzymes, has been demonstrated in fibroblasts.