del(15)(q11.2q13), Microdeletion syndrome
Fluorescence in situ Hybridization (FISH)
*performed by affiliate laboratory
5.0 mL (min. 3.0 mL) whole blood, sodium heparin
Protect from extreme temperature. Ship with cool pack (refrigerated). Saturday for Monday delivery only if sample is protected from extreme temperature.
Clotted specimen; Specimen exposed to extreme temperature; Anticoagulant toxic to cells; Insufficient number of cells
It is recommended that all FISH studies be done in conjunction with routine cytogenetic studies. If the FISH result is normal, a chromosome analysis allows identification of more complex abnormalities.
Prader-Willi syndrome (PWS), a rare neurogenetic disorder, represents the most common syndromatic obesity. Loss of the paternal genes on a specific region of chromosome 15 is the cause of this syndrome. Either two copies of the maternal genes is inherited (uniparental disomy) causing the loss of the paternal segment or there occurs a deletion of the genes on the paternal chromosome 15. The deletion can be detected by FISH, but specialized genetic testing is necessary to distinguish from Angelman syndrome.