diandric triploid hydatidiform mole
Monday 12 September 2011
Distinction of hydatidiform moles (HM) from nonmolar specimens and their subclassification as complete (CHM) versus partial hydatidiform mole (PHM) are important for clinical practice and investigational studies to refine ascertainment of risk of persistent gestational trophoblastic disease (GTD), which differs among these entities.
Immunohistochemical analysis of p57 expression, a paternally imprinted maternally expressed gene on 11p15.5, and molecular genotyping are useful for improving diagnosis.
CHMs are characterized by androgenetic diploidy, with loss of p57 expression due to lack of maternal DNA.
Loss of p57 expression distinguishes CHMs from both PHMs (diandric triploidy) and nonmolar specimens (biparental diploidy), which retain expression.
Specifically, molecular genotyping by short tandem repeat markers provided evidence to support interpretation as a PHM by demonstrating allele patterns and ratios most consistent with diandric triploidy, with evidence of loss of the maternal copy of chromosome 11 to explain the lack of p57 expression.