Prader-Willi Syndrome (cont.)
How common is Prader-Willi syndrome?
Prader-Willi syndrome affects an estimated 1 in 10,000 to 25,000 people.
What are the genetic changes related to Prader-Willi syndrome? Prader-Willi
syndrome is related to chromosome 15.
The OCA2 gene is associated with Prader-Willi syndrome.
Prader-Willi syndrome is caused by the loss of active genes in a specific
region of chromosome 15. People normally inherit one copy of this chromosome
from each parent. Some genes are active only on the copy that is inherited from
a person's father (the paternal copy). This parent-specific gene activation is
called genomic imprinting. Prader-Willi syndrome occurs when the region of the
paternal chromosome 15 containing these genes is missing.
Researchers are working to identify genes on chromosome 15 that are
responsible for the characteristic features of Prader-Willi syndrome. They have
not definitively connected many genes with specific signs and symptoms.
Researchers have determined, however, that a
deletion of the OCA2 gene on
chromosome 15 is associated with unusually fair skin and light-colored hair in
some affected individuals. The protein produced from this gene helps determine
the coloring (pigmentation) of the skin, hair, and eyes.
Most cases of Prader-Willi syndrome (about 70 percent) occur when a segment
of the paternal chromosome 15 is deleted in each
cell. In another 25 percent of
cases, a person with Prader-Willi syndrome 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,
Prader-Willi syndrome can also be caused by a chromosomal rearrangement called a
translocation, or by a mutation or other defect that abnormally inactivates
genes on the paternal chromosome 15. Each of these genetic changes results in a
loss of gene function in a critical region of chromosome 15.
Next: Can Prader-Willi syndrome be inherited? »
- Obesity - Learn about obesity and being overweight including the health risks, causes, review of weight loss diet plans, surgical and non-surgical treatments, and medications to treat the disease.
- Learning Disabilities - Read about learning disabilities, like the skills affected such as reading, writing, listening, speaking, reasoning, and mathematics. Causes, symptoms, diagnosis, and treatment information is included.
- Genetic Disease - Learn about genetic disease caused by abnormalities in an individual's genome. There are four types of genetic inheritance, single, multifactoral, chromosome abnormalities, and mitochondrial inheritance. Genetic testing is available for some genetic diseases.
Latest Medical News
Interactive Slideshows