Which syndrome is known for causing an uncontrollable urge to eat due to hormone imbalances?

Prader-Willi Syndrome is associated with an uncontrollable urge to eat, significantly influenced by hormonal imbalances, particularly involving ghrelin, a hormone that stimulates appetite. Individuals with this syndrome often experience a constant drive to eat, which can lead to obesity and related health issues if not appropriately managed. The underlying cause is linked to genetic factors, specifically the loss of function of genes on chromosome 15. This syndrome also encompasses other characteristics such as developmental delays, intellectual disability, and behavioral issues, but the most distinctive feature remains the hyperphagia, or excessive hunger.

In contrast, Cri du Chat Syndrome primarily involves characteristic physical features and developmental delays, while Down Syndrome is associated with a range of developmental and cognitive challenges but does not typically present with uncontrollable eating urges. Fragile X Syndrome is known for its association with intellectual disabilities and social/emotional challenges, but again, it does not involve the same appetite regulation issues found in Prader-Willi Syndrome. Therefore, the key aspect of Prader-Willi Syndrome being the hormone-related urge to eat makes it the correct answer to this question.