Citlalli puts on her shoes at her home in Mexico City, Mexico on March 26, 2017. Delia Citlalli Pineda Corzo, a 21-year-old Mexican girl, lives with her 42-year-old mother Diana Cristina Corzo Zárate in a two-room apartment in Mexico City. She was diagnosed with Prader-Willi syndrome at age four. At age 15, doctors detected that she had diabetes. Citlalli weighs 106 kilos (233.6 pounds) and stands 150 centimeters (4 feet 11 inches). She has a BMI of 50.5, making her morbidly obese. She also suffers from sleep apnea. Citlalli lacks the faculty of speech and cannot read, but her mother says they have developed their own form of communication. 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 Bénédicte Desrus)