Long-Term Survival Among Children With Trisomy 13 and Trisomy 18 by Cytogenetic Status

Area of Science:

• Genetics and Genomics
• Pediatric Medicine
• Reproductive Health

Background:

• Trisomy 13 (T13) and trisomy 18 (T18) are severe chromosomal abnormalities associated with high infant mortality.
• Prognosis and healthcare planning require understanding long-term survival differences between full and mosaic/partial trisomy forms.

Purpose of the Study:

• To compare 10-year survival rates between infants with full T13/T18 and those with mosaic or partial trisomy.
• To assess the impact of cytogenetic status on long-term survival for T13 and T18.

Main Methods:

• Retrospective, population-based cohort study using the Texas Birth Defects Registry (1999-2008 births).
• Kaplan-Meier survival estimates and Cox proportional hazards regression were used to analyze 10-year survival and mortality risks.
• Cytogenetic status (full vs. mosaic/partial trisomy) was the primary exposure variable.

Main Results:

• The study included 798 infants with T13 (n=295) or T18 (n=503).
• Ten-year survival was 8.5% for T13 and 8.6% for T18 overall.
• Survival to 10 years was significantly higher for mosaic/partial trisomy (25.0% for T13, 43.8% for T18) compared to full trisomy (4.9% for T13, 6.6% for T18) (P<.001).
• Full trisomy conferred increased 10-year mortality hazards (HR 2.00 for T13, HR 3.34 for T18) compared to mosaic/partial trisomy.

Conclusions:

• Cytogenetic status significantly influences long-term survival in infants with T13 and T18.
• Findings suggest a need to re-evaluate the prognosis for these conditions, especially mosaic trisomies, which are often considered incompatible with life.
• Results can inform treatment decisions and genetic counseling for affected families.