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Partial trisomy 13q identified by sequential fluorescence in situ hybridization
V V Rao1, N J Carpenter, M Gucsavas
1H.A. Chapman Institute of Medical Genetics, Children's Medical Center, Tulsa, Oklahoma, USA.
American Journal of Medical Genetics
|July 31, 1995
Summary
A rare genetic condition, partial trisomy 13q, was identified in a 19-month-old boy due to a chromosome 1 and 13 translocation. This chromosomal abnormality led to multiple congenital anomalies, including omphalocele and heart defects.
Area of Science:
- Genetics
- Pediatrics
- Cytogenetics
Background:
- Trisomy 13 (Down syndrome) is a well-known chromosomal disorder.
- Partial trisomy 13q, where only a segment of the 13th chromosome's long arm is duplicated, is less common.
- Accurate diagnosis of chromosomal abnormalities is crucial for understanding associated phenotypes.
Observation:
- A 19-month-old boy presented with omphalocele, malrotation, microcephaly, micrognathia, low-set ears, rocker-bottom feet, and congenital heart disease.
- Karyotypic analysis revealed an unbalanced karyotype (46,XY,-1,+der(1)) suggesting an extra chromosome segment.
- Conventional cytogenetics failed to identify the origin of the extra material on chromosome 1q.
Findings:
- Fluorescence in situ hybridization (FISH) confirmed the extra material on chromosome 1q was the terminal long arm of chromosome 13.
- The infant was diagnosed with partial trisomy 13q (q32-qter).
- The abnormality resulted from a probable balanced translocation between chromosomes 1 and 13 in the parents.
Implications:
- This case highlights the utility of advanced techniques like FISH in diagnosing complex chromosomal rearrangements.
- Understanding partial trisomy 13q is essential for genetic counseling and managing associated congenital anomalies.
- Further research into the specific breakpoints and their phenotypic correlations in partial trisomy 13q is warranted.