Thus, in familial BWS, where CDKN1C mutations are the most frequent abnormality [22], a scoring system designed to predict an abnormal ‘BWS methylation assay’ would not be appropriate as a normal IC1/2 methylation profile and a positive family history of maternally inherited BWS would indicate a requirement for CDKN1C mutation analysis [25]. The gene discussed is CDKN1C; the disease is Beckwith-Wiedemann syndrome.