TYMP and hyperinsulinemic hypoglycemia, familial, 4: In addition, erythrocyte encapsulation of thymidine kinase phosphorylase was reported to improve mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) syndrome in patients, a mitochondrial disease caused by thymidine phosphorylasethymine phosphorylase (TYMP) mutations leading to thymidine phosphorylase deficiency [120,121,122].