MTHFR and infection: Mthfr+/- mice, heterozygous for a null allele, were more resistant to P. berghei ANKA infection and mice that overexpressed MTHFR (through an additional copy of the human MTHFR gene (MTHFRTg mice) were more susceptible to infection, compared with wild-type animals (Mthfr+/+ mice); all mice had been fed standard mouse chow [3].