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molecular Analysis:
Prader-Willi Syndrome
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 on 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. Deletions, UPD, and imprinting defects lead to abnormal DNA methylation patterns. Analysis for PWS is based on detection of the parent specific methylation imprint at chromosome 15q11-13.
- Confirmation of a PWS diagnosis in affected individuals
- Individuals with atypical clinical findings
Our laboratory utilizes methylation sensitive polymerase chain reaction (PCR) and gel electrophoresis to detect the parent specific methylation imprint at the PWS region on chromosome 15q11-13.
This assay will detect greater than 99% of patients with PWS, including those cases caused by deletions, UPD, and imprinting defects. This assay will not detect the less than 1% of cases due to balanced chromosomal rearrangements with breakpoints within the 15q11-13 region.
Blood: For children, 3 - 5 cc collected in a purple top (EDTA) or yellow top (acid citrate dextrose) vacutainer tube. For infants, 1 - 2 cc is sufficient. Do not centrifuge or freeze. Sample may be refrigerated or stored at room temperature.
14 days
83890, 83894, 83898, 83912
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