Alpers- and MNGIE-like disease with disturbed CSF folate transport and an unusual mode of genetic transmission of POLG mutations: a case report

We report about a family with three of five siblings affected by a variable remitting-relapsing disease with epileptic seizures, coma and abdominal crises, and lethal outcome in all. In the youngest son and in one of his deceased brothers we identified two disease causing compound heterozygous POLG mutations. One of these was inherited from the mother, but the other was absent in the father`s blood, saliva, buccal swab and hair bulbs although his paternity was proven genetically. Thus, we assume germline mosaicism for this mutation in the father. Very low 5-methyltetrahydrofolate (5-MTHF) and absence of folate receptor-alpha was repeatedly found in the CSF of the youngest brother indicating a secondary cerebral folate transport deficiency. Folinic acid supplementation over 18 months resulted in some improvement of the neurological condition; however, it did not prevent progression of the systemic disease.