%0 Case Reports
%T A case of a parthenogenetic 46,XX/46,XY chimera presenting ambiguous genitalia.
%A Kawamura R
%A Kato T
%A Miyai S
%A Suzuki F
%A Naru Y
%A Kato M
%A Tanaka K
%A Nagasaka M
%A Tsutsumi M
%A Inagaki H
%A Ioroi T
%A Yoshida M
%A Nao T
%A Conlin LK
%A Iijima K
%A Kurahashi H
%A Taniguchi-Ikeda M
%J J Hum Genet
%V 65
%N 8
%D Aug 2020
%M 32277176
%F 3.755
%R 10.1038/s10038-020-0748-4
%X Sex-chromosome discordant chimerism (XX/XY chimerism) is a rare chromosomal disorder in humans. We report a boy with ambiguous genitalia and hypospadias, showing 46,XY[26]/46,XX[4] in peripheral blood cells. To clarify the mechanism of how this chimerism took place, we carried out whole-genome genotyping using a SNP array and microsatellite analysis. The B-allele frequency of the SNP array showed a mixture of three and five allele combinations, which excluded mosaicism but not chimerism, and suggested the fusion of two embryos or a shared parental haplotype between the two parental cells. All microsatellite markers showed a single maternal allele. From these results, we concluded that this XX/XY chimera is composed of two different paternal alleles and a single duplicated maternal genome. This XX/XY chimera likely arose from a diploid maternal cell that was formed via endoduplication of the maternal genome just before fertilization, being fertilized with both X and Y sperm.