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Trisomy 18 and a constitutional maternal translocation (2;18)
I E Teshima1, E J Winsor, M I Van Allen
1Department of Genetics, Hospital for Sick Children, Toronto, Canada.
American Journal of Medical Genetics
|July 1, 1992
Summary
Trisomy 18 cases usually assume nondisjunction. This study details a trisomy 18 case with a maternal translocation involving chromosomes 2 and 18, challenging typical assumptions.
Area of Science:
- Genetics
- Reproductive Biology
- Chromosomal Abnormalities
Background:
- Trisomy 18 (Edwards syndrome) is a genetic disorder caused by an extra copy of chromosome 18.
- Typically, trisomy 18 is attributed to meiotic nondisjunction during gamete formation.
- Parental chromosome analysis is often omitted due to the assumption of nondisjunction.
Observation:
- A case presenting with trisomy 18 was identified.
- Maternal chromosomal analysis revealed a translocation between chromosomes 2 and 18, specifically at bands (2;18)(q34;q12).
Findings:
- The presence of trisomy 18 in this case was associated with a maternal balanced translocation.
- This finding indicates that chromosomal translocations can be an underlying cause of trisomy 18, not just nondisjunction.
Implications:
- Revises the understanding of the etiology of trisomy 18.
- Suggests the importance of parental chromosomal analysis in specific trisomy 18 cases.
- Contributes to genetic counseling for families with chromosomal abnormalities.