Department of Obstetrics and Gynecology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
Department of Obstetrics and Gynecology, Niigata City General Hospital, Niigata, Japan.
J Hum Genet. 2017 Sep;62(9):803-808. doi: 10.1038/jhg.2017.45. Epub 2017 Apr 27.
The aim of this study was to investigate the parthenogenetic origin of fetiform teratoma by using molecular genetic studies and methylation status analyses. A fetiform teratoma was removed from a 35-year-old nulligravida woman. Genotyping of microsatellite marker loci, microarray analysis of single-nucleotide polymorphism (SNP) loci and methylation status analysis of the differentially methylated region (DMR) within the human IGF2-H19 locus were performed. Karyotypes of the host and the fetiform teratoma were 46, XX. The fetiform teratoma was homozygous at all loci and meiotic recombinations in the tumor were confirmed by SNP microarray analysis. Methylation analysis indicated that the host had both methylated and unmethylated IGF2-H19 DMR alleles, while the fetiform teratoma had unmethylated alleles only. Genetically, the fetiform teratoma had homozygous genotypes with meiotic recombination and a duplicated unmethylated host allele, indicating that it was a parthenogenetic tumor arising from a mature ovum after meiosis II. This is the first demonstration of a fetiform teratoma originating from a mature haploid ovum.
本研究旨在通过分子遗传学研究和甲基化状态分析来探究胎形畸胎瘤的单性生殖起源。我们从一位 35 岁的未产妇中切除了一个胎形畸胎瘤。对微卫星标记物、单核苷酸多态性（SNP）标记物的微阵列分析和 IGF2-H19 基因座内差异甲基化区域（DMR）的甲基化状态进行了分析。宿主和胎形畸胎瘤的核型均为 46, XX。胎形畸胎瘤在所有位点均为纯合子，并且 SNP 微阵列分析证实了肿瘤中的减数分裂重组。甲基化分析表明，宿主同时具有甲基化和非甲基化的 IGF2-H19 DMR 等位基因，而胎形畸胎瘤仅有非甲基化的等位基因。从遗传学角度来看，胎形畸胎瘤具有减数分裂重组的纯合基因型和一个重复的非甲基化宿主等位基因，这表明它是一个起源于第二次减数分裂后的成熟单倍体卵子的单性生殖肿瘤。这是首次证明胎形畸胎瘤起源于成熟的单倍体卵子。
