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FISH ANALYSIS:
Prader-Willi Syndrome (FISH Analysis)
Prader-Willi syndrome (PWS) is characterized by developmental delay, mild to moderate mental retardation, and learning disabilities. Infants have severe hypotonia, feeding difficulties, and failure to thrive. In early childhood, patients with PWS experience rapid weight gain leading to obesity. PWS is caused by the absence of the paternal PWS region of chromosome 15q11-q13 due to one of several mechanisms. In approximately 70% of cases, PWS is caused by a deletion in the paternal 15q11-q13 region. Approximately 28% of cases are caused by maternal uniparental disomy (UPD) of chromosome 15. Imprinting defects in the PWS region are responsible for less than 2% of cases. The remaining cases of PWS are due to balanced chromosomal rearrangements with breakpoints within the 15q11-13 region. FISH analysis will identify cases of Prader-Willi syndrome caused by a deletion of chromosome 15q11-13.
- Confirmation of a PWS diagnosis in affected individuals
- Individuals with atypical clinical findings
FISH analysis for PWS is performed on metaphase chromosomes to detect the deletion of chromosome 15q11-13. Chromosomal analysis and FISH is recommended for individuals being tested for PWS. For individuals with a normal karyotype, Prader-Willi Syndrome (Methylation Analysis) will detect all cases of PWS caused by deletion, UPD, and imprinting defects.
Blood: For adults and children, 3 – 5 cc collected in a sodium heparin (green top) vacutainer tube. For newborns, 2 cc is sufficient. Do not centrifuge or freeze. Store sample at room temperature.
8 days
88230, 88271, 88273, 88291
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