the presence of homozygote MTHFR C677T or dual heterozygous MTHFR C66T and A1298C, which leads to elevated Hcy and deficiency of vitamin B9 plasma levels, is correlated with an increased risk of cryptogenic stroke occurrence among adult Tunisian patients. This evidence concerns the gene MTHFR and hyperinsulinemic hypoglycemia, familial, 4.