Incidental STR profiling during thalassemia screening rescues a normal male fetus from Turner syndrome misdiagnosis following chorionic villus sampling.

Authors

Na Zuo, Minxia Ning, Weiling Hou, Weiwu Liu, Guanghong Wei, Xinghong Wang, Junyi Wei, Jizeng Li, Jujie Song, Jinjie Pan, Chong Luo, Zhenhua Bi, Chenghuan Zhang, Qingxiu Chen, Yanyan Chen, Yuanyuan Wen, Xiaomei Shen, Yunrong Qin, Yi Liang

Published in

Clinica chimica acta; international journal of clinical chemistry. Pages 122965. Nov 07, 2026. Epub Nov 07, 2026.

Abstract

Chorionic villus sampling (CVS) is widely established as the principal first-trimester prenatal diagnostic modality, yet a single biopsy may not reliably reflect fetal status owing to confined placental mosaicism, sampling-site variation, and culture-dependent clonal selection. We report a case in which incidental short tandem repeat (STR) profiling, performed for routine two-line thalassemia quality control, prevented termination of a chromosomally normal male fetus. A 24-year-old woman underwent CVS at 12⁺⁵ weeks for concurrent α-thalassemia genotyping and fetal karyotyping. Initial G-banded karyotyping of >20 cultured metaphases suggested non-mosaic 45,X; extension to >40 cells remained equivocal. Concurrent STR profiling revealed a male profile in uncultured villi but a non-male profile in cultured adherent cells, with concordant autosomal loci confirming fetal origin and excluding maternal cell contamination. Extended counting to 128 metaphases identified 46,XY in 6/128 (4.7%), revising the karyotype to 45,X [122]/46,XY [6]. CNV-seq confirmed a normal male profile in uncultured villi, whereas Y-chromosome signals in cultured cells were below the detection threshold. Non-invasive prenatal testing and amniocentesis at 17⁺² weeks both confirmed a normal male karyotype. A live male infant was delivered at 39⁺³ weeks, with isolated bilateral talipes equinovarus noted postnatally. This case demonstrates that both sampling-site heterogeneity and selective in vitro expansion of an abnormal cell line can produce a misleading CVS karyotype. Parallel STR profiling on uncultured and cultured villous fractions-even when performed incidentally for unrelated quality control-provides a critical safety net for detecting sex-chromosome discordance missed by conventional karyotyping alone.

PMID:
42998867
Bibliographic data and abstract were imported from PubMed on 08 Nov 2026.

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