This gene encodes an enzyme which catalyzes the reversible conversion of lactate and pyruvate, and NAD and NADH, in the glycolytic pathway. Mutations in this gene are associated with lactate dehydrogenase B deficiency. Pseudogenes have been identified on the X chromosome and on chromosome. Multiple alternatively spliced variants, encoding the same protein, have been identified. Rare LDHB variants result in deficiency of lactate dehydrogenase, a condition with no deleterious effects on health. LDHB deficiency is of interest to laboratory medicine mainly because it can cause misdiagnosis in those disorders in which elevation of serum LDH is expected. Lactate dehydrogenase deficiency can probably be considered a non-disease.