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.