SERPINC1 and hyperinsulinemic hypoglycemia, familial, 4: Several retrospective studies outlined the associations between IUGR and antithrombin III deficiency [13], PAI-I [6], MTHFR gene polymorphisms [14], etc. A recent meta-analysis and systematic review outlined the possible association between MTHFR 677C > T polymorphism and the development of IUGR [15].