A prenatally diagnosed Klinefelter syndrome case of 46,XX/47,XXY mosaicism with partial deletion of Y chromosome

Haruna Okubo; Yuki Ito; Tomoko Kawai; Hiromi Kamura; Michihiro Yamamura; Mikiko Kaneko; Akihiro Hasegawa; Ken Takahashi; Masahisa Kobayashi; Hiroshi Kawame; Kenichiro Hata; Osamu Samura; Aikou Okamoto

doi:10.1016/j.tjog.2024.12.030

A prenatally diagnosed Klinefelter syndrome case of 46,XX/47,XXY mosaicism with partial deletion of Y chromosome

Taiwan J Obstet Gynecol. 2025 Jul;64(4):707-710. doi: 10.1016/j.tjog.2024.12.030.

Authors

Affiliations

¹ Department of Obstetrics and Gynecology, The Jikei University School of Medicine, Minato-ku, Japan.
² Department of Obstetrics and Gynecology, The Jikei University School of Medicine, Minato-ku, Japan. Electronic address: yukinncho-yukinncho@jikei.ac.jp.
³ Department of Maternal-Fetal Biology, National Research Institute for Child Health and Development, Setagaya-ku, Japan.
⁴ Department of Clinical Genetics, The Jikei University Hospital, Minato-ku, Tokyo, Japan.
⁵ Department of Pediatrics, The Jikei University School of Medicine, Minato-ku, Japan.
⁶ Department of Human Molecular Genetics, Gunma University Graduate School of Medicine, Japan.

PMID: 40602970
DOI: 10.1016/j.tjog.2024.12.030

Abstract

Objective: Herein, we report the first case of 46,XX/47,XXY mosaicism with a partially deleted Y chromosome.

Case report: Chorionic villus sampling (CVS; G-banding) was performed due to increased nuchal translucency; the results showed a 46,XX karyotype. However, ultrasonography revealed male-type external genitalia. The stored CVS nuclear plate was reanalyzed to investigate the cause of the fetal sex discordance. The result showed a mosaic of a small supernumerary marker chromosome (sSMC) derived from Y chromosome. The infant was delivered vaginally at 39 weeks. Peripheral blood G-banding and fluorescence in situ hybridization for the infant indicated 47,XX, +mar [27]/46,XX [3] ish der(Y) (SRY+,DYZ1-). Single nucleotide polymorphism analysis of cord blood and chorionic villi revealed a deletion in chrY: 13,133,449-28,817,579. The infant was phenotypically male, with good growth and development at 24 months.

Conclusion: The fetal sex discordance led to a diagnosis of 46,XX/47,XXY mosaicism, which could guide postnatal management.

Keywords: Chorionic villus sampling; Klinefelter syndrome; Mosaicism; Prenatal diagnosis; Sex chromosome aberrations.

Publication types

Case Reports

MeSH terms

Chorionic Villi Sampling
Chromosome Deletion*
Chromosomes, Human, Y* / genetics
Female
Humans
In Situ Hybridization, Fluorescence
Infant, Newborn
Klinefelter Syndrome* / diagnosis
Klinefelter Syndrome* / genetics
Male
Mosaicism* / embryology
Pregnancy
Prenatal Diagnosis