Megavitamin responsive aminoacidopathies.

Several different vitamins, primarily members of the B complex, serve as coenzymes which activate apoenzymes to produce active holoenzymes. These cofactors participate in reactions in various ways. Even after a specific enzyme diagnosis is made in a patient, it is difficult, if not sometimes impossible, to determine if the patient will respond to a specific cofactor in vivo. The safety and ease of administering these compounds demand that therapeutic trials be undertaken. Doses (see Table 1) of several hundred to several thousand times the normal daily requirements must be given to the patient parenterally or by mouth. The studies in patients with B6-responsive disorders and with maple syrup urine disease would indicate that long term trials of these agents should be given even if there is no short term response. When efficacious, these compounds greatly simplify therapy for patients with inborn errors of amino acid metabolism.