High prevalence of maternal mosaic monosomy X in pregnant women in Vietnam

Abstract

Objective

To demonstrate the prevalence of maternal mosaic monosomy X (MMXO) in a cohort of pregnant women in Vietnam.

Methods

All 105,594 singleton pregnant women undergoing noninvasive prenatal screening (NIPS) between January 2019 and February 2021 in Vietnam were analyzed by measuring discordance between size- and count-based z-scores for chromosome X (ChrX) to identify suspected cases of MMXO and validated by fluorescence in situ hybridization (FISH) on maternal blood.

Results

We identified 295 (0.279%) suspected MMXO cases. After FISH analysis, MMXO was confirmed in 125 cases (42.37%), revealing the MMXO prevalence of 0.118% (95% CI: 0.097–0.139%) in this cohort.

Conclusion

We found a relatively high prevalence of MMXO in Vietnamese pregnant women and demonstrated a strong influence of MMXO on the ChrX z-score using a count-based method, resulting in false positives. The size-based method is not sensitive to MMXO and therefore achieves higher PPV.

Keywords:

• Maternal mosaic monosomy
• pregnant women
• Vietnam
• chromosome X
• z-score

Acknowledgments

We would like to acknowledge the contribution of all pregnant women who agreed to participate in this study. We thank Angela Marie Jansen, Ph.D., MHS of Angela Jansen and Associates, for assistance in editing the manuscript.

Ethical approval

The studies involving human participants were reviewed and approved by the institutional ethics committee of the University of Medicine and Pharmacy, Ho Chi Minh City, Vietnam (approval number 164/HDDD). Written informed consent to participate in this study was provided by the participants.

Disclosure statement

TTTN, NTKN, CTN, TDN, HG, HST, and MDP are employed by Gene Solutions, a company providing NIPS using the triSure method. No conflict of interest was reported by the remaining authors.

Data availability statement

All data are presented in this manuscript.

Additional information

Funding

This study was funded by Gene Solutions. The funder had no role in study design, data collection and analysis, publication decision, or manuscript preparation.