Prader-Willi syndrome is a rare genetic disorder that affects growth and development, found in one out of every 15,000 births. It is usually caused by the deletion of a part of chromosome 15 passed down by the father. It can also be caused by two copies of chromosome 15 coming from the mother, which is called uniparental disomy. It causes obesity, intellectual disability, and shortness in height. Prader-Willi syndrome is the most common genetic cause of childhood obesity. Usually doctors can identify Prader-Willi syndrome based on signs and symptoms. A definitive diagnosis can be made through a blood test. This genetic testing can identify abnormalities in the child's chromosomes that indicate Prader-Willi syndrome. The most common testing is “methylation analysis”, which detects the majority of cases. The other form of testing is “FISH” (fluorescent in-situ hybridization). Children with Prader-Willi Syndrome typically have Hypotonia (poor muscle tone, causes floppiness that is detected at birth). The child will typically have issues latching to the mothers’ breast and bottle due to lack of strength. Children with this syndrome also will have Hyperphagia, which causes an increased appetite and will eat an excessive amount of food, leading to obesity. Other signs of Prader-Willi syndrome are distinct facial features such as almond shaped eyes, narrow forehead; someone may be short in stature, typically have small hands and feet, delayed puberty, underdeveloped sex organs, poor physical development, delayed motor development, speech and behavioral problems.