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Interchange trisomy 9 due to maternal t(6;9) translocation
S Ninomiya1, K Narahara, Y Yokoyama
1Department of Pediatrics, Okayama University Medical School, Japan.
Acta Paediatrica Japonica : Overseas Edition
|October 1, 1994
Summary
This study reports the first case of interchange trisomy 9, resulting from a rare 3:1 segregation event in a maternal translocation. This genetic anomaly leads to severe developmental issues and is associated with trisomy 9 syndrome.
Area of Science:
- Genetics
- Human Genetics
- Reproductive Genetics
Background:
- Trisomy 9 is a severe chromosomal disorder with a high rate of fetal mortality.
- Interchange trisomy, resulting from 3:1 malsegregation, is a rare mechanism for aneuploidy.
- Previous reports of interchange trisomy are primarily associated with trisomy 21.
Observation:
- A neonate presented with intrauterine growth retardation, dysmorphic craniofacial features, cryptorchidism, cystic kidney, and skeletal anomalies.
- Cytogenetic analysis revealed a karyotype of 47,XY,-6, + der(6), + der(9)t(6;9)(q27;q21.1)mat, indicating interchange trisomy 9.
- The chromosomal abnormality originated from a maternal t(6;9) translocation.
Findings:
- This is the first reported case of interchange trisomy 9 arising from a maternal t(6;9) translocation.
- The patient's phenotype was consistent with the known features of trisomy 9 syndrome.
- The 3:1 segregation event, though rare, led to a live birth with full trisomy 9.
Implications:
- This case expands the understanding of rare mechanisms leading to trisomy 9.
- It underscores the importance of detailed cytogenetic analysis in cases of unexplained developmental abnormalities.
- The findings suggest that female carriers of reciprocal translocations involving chromosome 9 may be at risk for producing offspring with trisomy 9 through 3:1 segregation.