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[Chromosome abnormalities of human gametes]
B Sèle1, F Pellestor, S Rousseaux
1Laboratoire de Cytogénétique et Biologie de la Reproduction, Faculté de Médecine de Grenoble, La Tronche, France.
Reproduction, Nutrition, Development
|January 1, 1990
Summary
Human gamete studies reveal high aneuploidy rates, with 27% of oocytes showing chromosomal abnormalities. This suggests no selection against abnormal sperm in translocation carriers, impacting understanding of conception outcomes.
Area of Science:
- Reproductive biology
- Human genetics
- Cytogenetics
Background:
- Human newborns with chromosomal abnormalities represent survivors of more numerous affected conceptions.
- Studying conceptuses directly is unfeasible, and determining parental origin of chromosomal errors is methodologically challenging.
- Human gametes offer a viable alternative for studying chromosomal abnormality mechanisms.
Observation:
- Large-scale studies estimate a 10% abnormality rate in sperm from normal men.
- Reciprocal translocation carriers showed no evidence of selection against abnormal sperm.
- Approximately 30% of oocytes fail fertilization in IVF, making them available for cytogenetic study.
Findings:
- Analysis of 405 oocytes II revealed a 27% aneuploidy rate, indicating the first meiotic non-disjunction rate.
- This aneuploidy frequency was independent of ovulation stimulation methods.
- Maternal aging did not correlate with an increased aneuploidy rate in the studied oocytes.
Implications:
- High oocyte aneuploidy rates challenge assumptions about early embryonic viability.
- Findings suggest potential mechanisms for chromosomal abnormalities in human reproduction.
- Further research into gamete aneuploidy is crucial for understanding infertility and developmental disorders.