CONGENITAL ERRORS OF FOLATE METABOLISM

The presence in yeast and leaves of a potent anti-anaemic factor with anti-megaloblastic properties called 'folic acid' has been identified for more than 50 years. The most prominent effect of folic acid deficiency is the appearance of a macrocytic megaloblastic anaemia, often associated with a leukopenia and thrombocytopenia. In fact all cells with a rapid turnover rate are affected because of the involvement of folic acid in DNA synthesis. Folic acid deficiency is also harmful to the central nervous system as shown by the increasing number of reports of folate-responsive neuropathy (Reynolds et al, 1973; Manzoor and Runcies, 1976; Botez et al, 1979; Monaco et al, 1983) and by the neurological damage seen in most patients suffering from inborn errors of folate metabolism (Niederwieser, 1979).