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Identification of mosaicism in Prader-Willi syndrome using fluorescent in situ hybridization
P A Mowery-Rushton1, J M Hanchett, W B Zipf
1Magee Womens Research Institute, Magee Womens Hospital, University of Pittsburgh, Pennsylvania 15213-3180, USA.
Abstract:
We report on our findings of 4 patients with mosaicism for a deletion of chromosome 15, most commonly associated with Prader-Willi syndrome (PWS). We examined a series of typical and atypical PWS patients in order to identify cytogenetically undetected deletions, using fluorescence in situ hybridization. In 4 of the patients analyzed we detected a deletion in 14-60% of peripheral blood leukocytes, using four commercially available probes. Our results indicate that mosaicism may play a role in the etiology of some PWS cases. These findings may be especially useful in patients who display discrepancies between clinical phenotype and established diagnostic criteria. Methylation and microsatellite polymorphism analyses of 2 patients with low-level mosaicism failed to identify the deletion. We propose that fluorescence in situ hybridization is the most effective method for detecting somatic mosaicism, since a large number of cells can be individually examined for the presence or absence of a specific deletion.
Insights
Mosaicism, a genetic condition where cells have different genetic makeup, was identified in four patients with Prader-Willi syndrome (PWS). Fluorescence in situ hybridization effectively detected these deletions, aiding diagnosis in complex cases.
Area of Science:
- Genetics
- Molecular Biology
- Clinical Diagnostics
Background:
- Prader-Willi syndrome (PWS) is a complex genetic disorder.
- Standard diagnostic methods may not detect all genetic variations.
- Identifying the genetic basis of PWS is crucial for accurate diagnosis and management.
Observation:
- Four patients with PWS exhibited mosaicism for a deletion on chromosome 15.
- Deletions were detected in 14-60% of peripheral blood leukocytes using fluorescence in situ hybridization (FISH).
- Traditional methylation and microsatellite analyses were insufficient for detecting low-level mosaicism in two patients.
Findings:
- Somatic mosaicism for chromosome 15 deletions is present in a subset of PWS patients.
- FISH is a highly sensitive method for detecting deletions in mosaic PWS cases.
- The presence of mosaicism can explain clinical phenotypes inconsistent with standard diagnostic findings.
Implications:
- FISH analysis should be considered for PWS patients with atypical clinical presentations.
- This finding expands the understanding of PWS etiology and genetic heterogeneity.
- Improved diagnostic accuracy for PWS can lead to better patient care and genetic counseling.