In the light of these observations and the apparently milder phenotypic effects of maternal NLRP2 inactivation than NLRP7 inactivation (Beckwith-Wiedemann syndrome and molar pregnancy respectively) it might be predicted that clinical heterogeneity/incomplete penetrance would be a feature of maternal NLRP2 inactivation. This evidence concerns the gene NLRP7 and Beckwith-Wiedemann syndrome.