[Diet therapy and coenzyme therapy in hereditary metabolic diseases]

A greater number of inherited metabolic disorders can now be treated with special diets or cofactors. Recent progress is illustrated by the example of various hyperphenylalaninaemias (HPHE), of maple syrup urine disease (MSUD) and of various homocystinurias (HCY). Of special importance for the future is a severe embryopathy in infants of mothers with HPHE and its possible prevention by reintroducing a phenylalanine - restricted diet for the mother before conception. Of considerable scientific interest and therapeutic impact is also the treatment of patients with HPHE due to tetrahydrobiopterin deficiency. This consists in substituting the patients' metabolism with this cofactor of phenylalanine hydroxylase as well as with neurotransmitters. Cofactor deficiencies have also been described in MSUD and HCY, and substitution with high doses of thiamine and pyridoxin has been successful. The management of the acute metabolic derangement of neonatal MSUD is a great therapeutic challenge even to experienced metabolic centres. Rational therapy for homocystinurias due to remethylation defects is still being explored. In siblings with methylenetetrahydrofolate reductase deficiency we used leucovorin for the first time and with success.