caused by endogenous (polymorphisms of the
homocysteine/folate cycle genes) and exogenous factors (dietary defi-
ciency of folate), may be significantly involved in the pathogenesis of
congenital diseases. Thus, discerning the many factors that may affect
the methyl balance and understanding the pathophysiology of these
congenital diseases from the “methylation point of view” stillremaina
great challenge.