A fetus coexisting with a complete hydatidiform mole with trisomy 9 of maternal origin

Androgenetic Complete Hydatidiform Moles With p57KIP2-Positive Immunostaining

OBJECTIVES

Complete hydatidiform moles (CHMs) are androgenetic and have a high rate of progression to gestational trophoblastic neoplasia (GTN). CHMs are negative when immunostained for p57KIP2 protein, the product of the maternally expressed gene on chromosome 11p15.5, whereas biparental partial hydatidiform moles and hydropic abortion are positive for p57KIP2. This study presents two cases of p57KIP2-positive androgenetic CHMs and explores the cause of this inconsistency.

METHODS

Androgenetic CHMs were diagnosed using multiplex short tandem repeat polymorphism analysis. Single-nucleotide polymorphism arrays were performed for molecular karyotyping.

RESULTS

Among the consecutive 188 androgenetic CHMs, two cases were positive for p57KIP2. The first case remitted spontaneously, whereas the second case developed into low-risk GTN. The first case was positive for p57KIP2 in all villi. The karyotype was 48,XX,+7,+11, with the additional chromosome 11 confirmed to be of maternal origin. The second case presented a mosaic of both positively and negatively stained villi. The karyotype was 46,XX.

CONCLUSIONS

The cause of one of the CHMs was trisomy with an additional maternal chromosome 11. Although rare, the confirmation of p57KIP2-positive androgenetic CHM status is necessary to manage GTN risk.

Parental contribution to trisomy in heterozygous androgenetic complete moles

Complete hydatidiform moles (CHMs) comprise a proliferative trophoblastic disorder and are known to be androgenetic and diploid. Androgenetic CHMs are classified as having monospermic and dispermic origins. Rarely, some CHMs have other genetic constitutions, such as biparental diploid or tetraploid. Previous studies have shown the possibility that androgenetic heterozygous CHMs have an additional chromosome with high frequency. This study aimed to comprehensively analyse the molecular karyotyping of androgenetic dispermic CHMs and the parental contribution of their additional chromosomes. Single-nucleotide polymorphism arrays were performed with the genomic DNA of CHMs and patients. The B allele frequency and selected B allele frequency plotting of CHM were visualised. Among the 31 dispermic CHMs, eight showed trisomy and one showed double trisomy; of the 10 additional chromosomes, seven were of maternal original and three were of paternal origin. In addition, three disomic chromosomes comprised one maternal and one paternal chromosome, although these should theoretically have had two paternal chromosomes in the case of androgenetic CHMs. The subclassification of heterozygous CHMs, with or without maternal contribution, is a new approach and could be a candidate indicator of gestational trophoblastic neoplasia risk.

Genome-wide single nucleotide polymorphism array analysis unveils the origin of heterozygous androgenetic complete moles

Hydatidiform moles are abnormal pregnancies, which show trophoblastic hyperplasia. Most often, the nuclear genome in complete hydatidiform moles (CHMs) is composed of only paternal chromosomes. Diploid androgenetic conceptuses can be divided into homozygous and heterozygous CHMs. Heterozygous CHMs originate from two sperms or a diploid sperm, the distinction of which has not been established. Here, we assessed the origin of heterozygous CHMs using single nucleotide polymorphism (SNP) array. Thirteen heterozygous CHMs were analysed using B allele frequency (BAF) plotting to determine the centromeric zygosity status of all chromosomes. One case was from the duplication of a single sperm with an XY chromosome. In the other twelve cases, centromeric zygosity was random, i.e. mixed status. Thus, the twelve heterozygous CHMs were considered to be of dispermic origin but not diploid sperm origin. BAF plotting of SNP array can be a powerful tool to estimate the type of hydatidiform moles.