Supplementary Material for: Novel Nonsense Mutation in the <b><i>NLRP7</i></b> Gene Associated with Recurrent Hydatidiform Mole

<b><i>Aim:</i></b> This study aimed to clarify the genetic and epigenetic features of recurrent hydatidiform mole (RHM) in Japanese patients. <b><i>Methods:</i></b> Four Japanese isolated RHM cases were analyzed using whole-exome sequencing. Villi from RHMs were collected by laser microdissection for genotyping and DNA methylation assay of differentially methylated regions (DMRs). Single nucleotide polymorphisms of <i>PEG3</i> and <i>H19</i> DMRs were used to confirm the parental origin of the variants. <b><i>Results:</i></b> A novel homozygous nonsense mutation in <i>NLRP7</i> (c.584G>A; p.W195X) was identified in 1 patient. Genotyping of one of her molar tissue revealed that it was biparental but not androgenetic in origin. Despite the fact that the RHM is biparental, maternally methylated DMRs of <i>PEG3</i>, <i>SNRPN</i> and <i>PEG10</i> showed complete loss of DNA methylation. A paternally methylated DMR of <i>H19</i> retained normal methylation. <b><i>Conclusions:</i></b> This is the first Japanese case of RHM with a novel homozygous nonsense <i>NLRP7</i> mutation and a specific loss of maternal DNA methylation of DMRs. Notably, the mutation was identified in an isolated case of an ethnic background that has not previously been studied in this context. Our data underscore the involvement of <i>NLRP7</i> in RHM pathophysiology and confirm that DNA methylation of specific regions is critical.