Alleles and haplotypes of the Glu429Ala polymorphism of the MTHFR gene did not affect the risk of developing MI. In all likelihood, the prothrombotic effect of polymorphisms of this gene can manifest itself when it is combined with other genetic mutations that affect the risk of developing MI or when a combination of hereditary and acquired factors is present. Such combinations are a much greater threat than the presence of one genetic disorder of the coagulation system.