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Duplication 20p identified via fluorescent in situ hybridization
K A LeChien1, E McPherson, A M Estop
1Western Pennsylvania Hospital, Department of Medical Genetics, Pittsburgh 15224.
American Journal of Medical Genetics
|April 1, 1994
Summary
A rare genetic condition, 20p duplication, was identified in a child due to a de novo translocation between chromosomes 20 and 21. Fluorescent in situ hybridization (FISH) confirmed the chromosomal abnormality.
Area of Science:
- Genetics
- Cytogenetics
- Pediatric Medicine
Background:
- A de novo translocation t(20;21) can lead to complex chromosomal rearrangements.
- Identifying the origin of extra chromosomal material is crucial for diagnosing genetic disorders.
Observation:
- A 3-year-old girl presented with developmental delay and minor anomalies, exhibiting a phenotype suggestive of 20p trisomy.
- Her karyotype revealed a 21p+ chromosome and an additional small marker chromosome.
Findings:
- Conventional cytogenetics failed to identify the source of the extra material on chromosome 21p and the marker chromosome.
- Fluorescent in situ hybridization (FISH) successfully characterized the 21p+ and marker chromosomes, confirming dup(20p) from 3:1 segregation.
Implications:
- This case highlights the utility of FISH in characterizing complex chromosomal abnormalities.
- Accurate genetic diagnosis is essential for understanding developmental disorders and providing appropriate genetic counseling.