About 5–10% of cases exhibiting Beckwith-Wiedemann syndrome (BWS), an overgrowth syndrome characterized by macrosomia, macroglossia, and abdominal wall defects, are caused by loss-of-function mutations of cyclin-dependent kinase inhibitor 1C (CDKN1C, p57kip2) [108–112]. The gene discussed is CDKN1C; the disease is macroglossia.