Genetic Disorders: Prader-Willi Syndrome

Genetic disorders are one or more abnormalities in genomes, a genetic disorder is usually apparent at birth. Genetic disorders are usually rare and impact one in several thousands, if not millions. Prader-Willi Syndrome is a genetic disorder that causes obesity, intellectual disability, and shortness in height. PWS was first described by Swiss doctors Andrea Prader, Alexis Labhart, and Heinrich Willi in 1956 based on the clinical characteristics of nine children they examined. PWS is recognized as the most common genetic cause of life-threatening childhood obesity. It is estimated that in one 12,000 to 15,000 people has Prader-Willi syndrome. Although considered as a “rare” disorder, PWS is one of the most common conditions seen in genetic
The most common symptoms of Prader-Willi syndrome are behavior problems intellectual disability, and short stature. Hormonal symptoms include delayed puberty and constant hunger leading to obesity. There is no cure for Prader-Willi syndrome but many patients will benefit from a supervised diet. Some symptoms can be treated with hormone therapy. Most causes of PWS are not inherited, particularly those caused by a deletion in the paternal chromosome 15 or by maternal (relating to the mother) uniparental disomy. These genetic changes occur as random events during the formation of reproductive cells or in early embryonic development. This phenomenon is called maternal uniparental disomy. Rarely, Prader-Willi syndrome can also be caused by a chromosomal rearrangement called a translation, or by a mutation or other defect that abnormally turns off genes on the paternal chromosome
A team of health professionals will likely work with you to manage the condition. You need good nutrition for infants, human growth hormone treatment, sex hormone treatment, healthy diet, treatment of sleep disturbances, overall development, mental health care, and transition to adult care. Physical therapy can restore muscle strength and function through exercise. Behavior therapy is focused on modifying harmful behaviors associated with psychological distress. A “FISH” (fluorescent in-situ hybridization) test will identify people with Prader-Willi syndrome due to deletion, but will not identify those who have Prader-Willi syndrome by “UPD” (uniparental disomy) or an imprinting error. A Chromosome Microarray test detects most chromosome deletions, even many small “atypical” sizes, and it will also detect many cases of UPD. It doesn’t detect all cases of Prader-Willi syndrome and specifically those with imprinting defects. UPD and imprinting defect testing is a DNA test that usually requires blood from the patient and both parents for accurate interpretation. The risk to the sibs of an affected child of having Prader-Willi syndrome depends on the genetic mechanism that resulted in the absence of expression of the paternally contributed 15q11.2-q13 region. The risk to sibs is typically less that 1% if the affected has a deletion, up to 50%, if the affected child has an