TEST NAME
– Prader-Willi Syndrome (FISH)
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ABOUT TEST
– Prader-Willi syndrome (PWS) is a complex genetic condition that affects many parts of the body. In infancy, this condition is characterized by hypotonia, feeding difficulties, poor growth, and delayed development. Beginning in childhood, affected individuals develop an insatiable appetite, which leads to chronic hyperphagia and obesity. Some people with PWS, particularly those with obesity, also develop type 2 diabetes.
PWS is caused by the loss of function of genes in a particular region of chromosome 15. Most cases of PWS (about 70%) occur when a segment of the paternal chromosome 15 is deleted in each cell. People with this chromosomal change are missing certain critical genes in this region because the genes on the paternal copy have been deleted, and the genes on the maternal copy are turned off (inactive). In another 25 percent of cases, a person with PWS has two copies of chromosome 15 inherited from his or her mother (maternal copies) instead of one copy from each parent. This phenomenon is called maternal uniparental disomy. Rarely,PWS can also be caused by a chromosomal translocation, or by a mutation or other defect that abnormally turns off (inactivates) genes on the paternal chromosome 15.
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GENES TESTED
– SNRPN (15q11)/PML (15q24)
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SAMPLE REQUIREMENTS
– Green
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TAT
– 14
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Related Tests
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