Urine Sorbitol and Xylitol for the Diagnosis of Sorbitol Dehydrogenase Deficiency–Related Neuropathy

Sorbitol dehydrogenase (SORD) deficiency, due to biallelic loss-of-function variants in the SORD gene, is a recently recognized cause of autosomal recessive hereditary neuropathy. Specific diagnosis is difficult on clinical grounds alone, and molecular genetic testing of SORD is complicated by the presence of a pseudogene. Biochemical testing of serum sorbitol is suggested as a potential biomarker. We report a novel urine biochemical profile of elevated excretion of sorbitol and a second polyol, xylitol, to aid in the identification of individuals with SORD-related neuropathy.