CDKN1C and complete hydatidiform mole: Biparental complete moles are generally the result of abnormal methylation of maternal alleles [16] and usually show complete lack of p57 staining [12], although maternal homozygous or compound heterozygous mutations in the NLRP7 and C6orf221 (KHDC3L) genes have also been implicated when fetuses are shown to be diploid and biparental in origin [17-19].