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Non-mosaic trisomy 16 in a third-trimester fetus
M K Yancey1, E L Hardin, C Pacheco
1Department of Obstetrics and Gynecology, Tripler Army Medical Center, Honolulu, Hawaii, USA.
Obstetrics and Gynecology
|May 1, 1996
Summary
Full trisomy 16 is rare in near-term fetuses, with this case showing paternal origin of the extra chromosome. This finding challenges previous assumptions about trisomy 16 survival and expression.
Area of Science:
- Genetics
- Reproductive Biology
- Fetal Development
Background:
- Trisomy 16 is the most common chromosomal abnormality in spontaneous first-trimester abortions.
- Previous studies indicated a maternal origin for the extra chromosome 16 in aborted fetuses.
- Full trisomy 16 was considered incompatible with survival beyond the second trimester.
Observation:
- A near-term stillborn fetus presented with oligohydramnios, severe growth restriction, and dysmorphic features.
- Karyotyping revealed full trisomy 16 (47, XX,+16) in fetal tissues and chorionic villi.
- Parental origin studies identified paternal non-disjunction as the source of the extra chromosome 16.
Findings:
- This report documents a rare case of a near-term fetus with full trisomy 16.
- The extra chromosome 16 was paternally derived, contrasting with previous observations of maternal origin.
- The fetus exhibited severe growth restriction and dysmorphic features.
Implications:
- Paternal origin of trisomy 16 may influence phenotypic expression and fetal outcomes.
- This case expands the known spectrum of trisomy 16 viability.
- Further research is needed to understand the role of parental origin in trisomy 16 phenotypes.