An annual meeting organized by Fundacion Mar?a Jose, the Prader-Willi association of Mexico, in Mexico City, Mexico on April 9, 2017. Prader-Willi Syndrome (PWS) is a rare genetic disorder caused by an abnormality in chromosome 15. In?newborns?symptoms include?weak muscle tone (hypotonia), poor appetite and slow development. In childhood the person experiences a sensation of constant hunger no matter how much he/she eats which often leads to?obesity?and?Type 2 diabetes. There may also be mild to moderate?intellectual impairment?and behavioral problems. Physical characteristics include a narrow forehead, small hands and feet, short in stature, and light skin color. Prader-Willi syndrome has no known cure. However, with early diagnosis and treatment such as growth hormone therapy, the condition may improve. Strict food supervision is typically required. PWS?affects an estimated 1 in 10,000 to 30,000 people worldwide. (Photo by Benedicte Desrus/Sipa USA)