️ Episode 179: Mosaicism for Autosomal Trisomies: Maternal Age, UPD, and Reproductive History in 1,266 Cases
In this episode of PaperCast Base by Base, we explore a comprehensive literature analysis of 1,266 reported cases of autosomal trisomy mosaicism, contrasting prenatal cohorts—true fetal mosaicism and confined placental mosaicism—with postnatal diagnoses to clarify how maternal age and reproductive history relate to outcomes and uniparental disomy.

Study Highlights:
The authors screened 596 publications and assembled 948 prenatal and 318 postnatal mosaicism cases to compare outcome patterns and demographics. They found that advanced maternal age was more common in pregnancies with normal outcomes than in those with abnormal outcomes (73% vs 56%), while pregnancies ending in fetal loss showed a 50% advanced maternal age rate. Mosaic carriers with concomitant uniparental disomy of chromosomes 7, 14, 15, or 16 had markedly higher advanced maternal age than those with biparental disomy overall (78% vs 48%), suggesting age-associated biases in trisomy rescue. Reporting of reproductive history was limited, but prior fetal loss was nearly twice as frequent among mothers in the postnatal cohort compared with the prenatal cohort (30% vs 16%), and prior chromosomal abnormalities in earlier pregnancies appeared substantially enriched relative to non-mosaic series.

Conclusion:
These findings challenge assumptions drawn from non-mosaic trisomies and indicate that maternal age and reproductive history shape both outcomes and the likelihood of uniparental disomy in autosomal trisomy mosaicism, motivating better standardized reporting and registry-based studies.

Reference:
Kovaleva, N. V.; Cotter, P. D. Mosaicism for Autosomal Trisomies: A Comprehensive Analysis of 1266 Published Cases Focusing on Maternal Age and Reproductive History. Genes 2024, 15, 778. https://doi.org/10.3390/genes15060778

License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/

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Chapters

• (00:00:00 ) - Causes of Trisomy 21 in maternal age
• (00:01:59 ) - The Case of Mosaicism in America
• (00:02:38 ) - Common Trisomy 4, Non-Moist mosaic cases
• (00:03:09 ) - Autosomal mosaicism: The science, methodology, and impact
• (00:07:57 ) - The mosaic trisomies in babies
• (00:08:52 ) - Maternal age and mosaicism
• (00:12:26 ) - Mosaic Trisomy Recurrence Risk