Molecular genetic studies of complete hydatidiform moles

Abstract

Complete hydatidiform moles (CHM) are abnormal pregnancies with no fetal development resulting from having two paternal genomes with no maternal contribution. It is important to distinguish CHM from partial hydatidiform moles, and non-molar abortuses, due to the increased risk of gestational trophoblastic neoplasia. We evaluated a series of products of conception (POC) (n=643) investigated by genome-wide microarray comparative genomic hybridisation (CGH) with the aim of refining our strategy for the identification of complete moles. Among 32 suspected molar pregnancies investigated by STR genotyping to supplement microarray CGH testing, we found 31.3% (10/32) CHM; all identified among 3.6% (10/272) early first trimester POC. We suggest that when using microarray CGH that genotyping using targeted STR analysis should be performed for all POC referrals to aid in the identification of CHM.

Keywords: Complete hydatidiform mole (CHM); Quantitative Fluorescent Polymerase Chain Reaction (QF-PCR); genotyping; molar pregnancy; products of conception (POC).

Figure 1

Frequency of chromosomal abnormalities among all samples (n=643). Note: Del, deletion; Dup, duplication.

Figure 2

STR genotype representing a diploid Complete Mole analysed using the QST*R kit (Elucigene). All autosomes (chromosomes 13, 18 and 21) show homozygous alleles. A single allele for Amelogenin X/Y and two alleles for the TAF9 marker is consistent with two X chromosomes.

Figure 3

Genetic testing strategy for POC specimens to identify complete hydatidiform molar pregnancies. POC, products of conception.