Genetic origin and imprinting in hydatidiform moles. Comparison between DNA polymorphism analysis and immunoreactivity of p57KIP2.

To evaluate whether p57KIP2 expression is concordant with the result of DNA polymorphism analysis in molar pregnancy. Eleven molar pregnancies diagnosed by pathologic findings between October 2002 and April 2004 were studied. Histopathologic diagnosis, DNA polymorphism analysis and p57KIP2 immunohistochemistry were investigated. DNA polymorphism analysis identified 3 biparental conceptuses as well as 4 dispermic androgenetic complete moles (CMs) and 4 suggestive monospermic CMs. Distinctly positive nuclear immunoreactivity of p57KIP2 was observed in a significant proportion of the villous cytotrophoblast and mesenchyme (30-60% of cells positive) in 3 cases of biparental conceptuses proven by DNA polymorphism. In contrast, p57KIP2 expression was negative (< 5% positive cells) in either the villous cytotrophoblast or mesenchyme in 8 cases of androgenetic conceptuses proven by DNA polymorphism. In all 11, p57KIP2 immunostaining was observed in the nuclei of extravillous trophoblasts that served as internal positive controls. Negative p57KIP2 immunoreactivity (paternally imprinted, maternally expressed gene) was in perfect concordance with the androgenetic origin of molar pregnancies proven by DNA polymorphism. The results suggest that p57KIP2 immunoreactivity, which can be performed in routine pathologic examinations, is a promising ancillary diagnostic tool to differentiate androgenetic CM from biparental conceptuses.