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A case of a parthenogenetic 46,XX/46,XY chimera presenting ambiguous genitalia.

ABSTRACT: 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.

SUBMITTER: Kawamura R

PROVIDER: S-EPMC7324356 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature

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A case of a parthenogenetic 46,XX/46,XY chimera presenting ambiguous genitalia.

Kawamura Rie R Kato Takema T Miyai Shunsuke S Suzuki Fumihiko F Naru Yuki Y Kato Maki M Tanaka Keiko K Nagasaka Miwako M Tsutsumi Makiko M Inagaki Hidehito H Ioroi Tomoaki T Yoshida Makiko M Nao Tomoya T Conlin Laura K LK Iijima Kazumoto K Kurahashi Hiroki H Taniguchi-Ikeda Mariko M

Journal of human genetics 20200410 8

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 sug ...[more]

PMID: 32277176

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Project description:Steroidogenic factor 1 (NR5A1, SF-1, Ad4BP) is a transcriptional regulator of genes involved in adrenal and gonadal development and function. Mutations in NR5A1 have been among the most frequently identified genetic causes of gonadal development disorders and are associated with a wide phenotypic spectrum. In 46,XY individuals, NR5A1-related phenotypes may range from disorders of sex development (DSD) to oligo/azoospermia, and in 46,XX individuals, from 46,XX ovotesticular and testicular DSD to primary ovarian insufficiency (POI). The most common 46,XY phenotype is atypical or female external genitalia with clitoromegaly, palpable gonads, and absence of Müllerian derivatives. Notably, an undervirilized external genitalia is frequently seen at birth, while spontaneous virilization may occur later, at puberty. In 46,XX individuals, NR5A1 mutations are a rare genetic cause of POI, manifesting as primary or secondary amenorrhea, infertility, hypoestrogenism, and elevated gonadotropin levels. Mothers and sisters of 46,XY DSD patients carrying heterozygous NR5A1 mutations may develop POI, and therefore require appropriate counseling. Moreover, the recurrent heterozygous p.Arg92Trp NR5A1 mutation is associated with variable degrees of testis development in 46,XX patients. A clear genotype-phenotype correlation is not seen in patients bearing NR5A1 mutations, suggesting that genetic modifiers, such as pathogenic variants in other testis/ovarian-determining genes, may contribute to the phenotypic expression. Here, we review the published literature on NR5A1-related disease, and discuss our findings at a single tertiary center in Brazil, including ten novel NR5A1 mutations identified in 46,XY DSD patients. The ever-expanding phenotypic range associated with NR5A1 variants in XY and XX individuals confirms its pivotal role in reproductive biology, and should alert clinicians to the possibility of NR5A1 defects in a variety of phenotypes presenting with gonadal dysfunction. Birth Defects Research (Part C) 108:309-320, 2016. © 2016 The Authors Birth Defects Research Part C: Embryo Today: Reviews Published by Wiley Periodicals, Inc.

Project description:Background and objectives: XX male syndrome is part of the disorders of sex development (DSD). The patients generally have normal external genitalia and discover their pathology in adulthood because of infertility. There are no guidelines regarding XX male syndrome, so the aim of our study was to evaluate the literature evidence in order to guide the physicians in the management of these type of patients. Materials and Methods: We performed a systematic review of the available literature in September 2018, using MEDLINE, Web of Science, Embase and Google Scholar database to search for all published studies regarding XX male syndrome according to PRISMA guidelines. The following search terms were used: "46 XX male", "DSD", "infertility", "hypogonadism". Results: After appropriate screening we selected 37 papers. Mean (SD) age was 33.14 (11.4) years. Hair distribution was normal in 29/39 patients (74.3%), gynecomastia was absent in 22/39 cases (56.4%), normal testes volume was reported in 0/14, penis size was normal in 26/32 cases (81.2%), pubic hair had a normal development in 6/7 patients (85.7%), normal erectile function was present in 27/30 cases (90%) and libido was preserved in 20/20 patients (100%). The data revealed the common presence of hypergonadotropic hypogonadism. All patients had a 46,XX karyotype. The sex-determining region Y (SRY) gene was detected in 51/57 cases. The position of the SRY was on the Xp in the 97% of the cases. Conclusions: An appropriate physical examination should include the evaluation of genitalia to detect cryptorchidism, hypospadias, penis size, and gynecomastia; it is important to use a validated questionnaire to evaluate erectile dysfunction, such as the International Index of Erectile Function (IIEF). Semen analysis is mandatory and so is the karyotype test. Abdominal ultrasound is useful in order to exclude residual Müllerian structures. Genetic and endocrine consultations are necessary to assess a possible hypergonadotropic hypogonadism. Testicular sperm extraction is not recommended, and adoption or in vitro fertilization with a sperm donor are fertility options.

Dataset Information

A case of a parthenogenetic 46,XX/46,XY chimera presenting ambiguous genitalia.

Publications

A case of a parthenogenetic 46,XX/46,XY chimera presenting ambiguous genitalia.

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