The right answer is chromosome 15.
Prader-Willi syndrome (PWS) is a rare genetic disorder characterized by hypothalamic-pituitary dysfunction associated with major hypotonia during the neonatal period and the first two years of life. From childhood to adulthood, the main problems are the appearance of hyperphagia with the risk of morbid obesity, learning difficulties and behavioral problems, even major psychiatric disorders.
In this syndrome, the affected region (15q11-q13) is located on the long arm of chromosome 15. On chromosome 15 of paternal origin, the genes of the 15q11-q13 region are functional, whereas they do not fulfill their function on chromosome 15 of maternal origin (inactivation by methylation).
