What is Prader-Willi syndrome primarily characterized by?

Prader-Willi syndrome is primarily characterized by reduced muscle tone, known as hypotonia, and obesity. These features are significant in the clinical presentation of the syndrome. Individuals with Prader-Willi syndrome often have weak muscle tone at birth, which can lead to difficulties with feeding and motor skills during infancy. As they grow, they typically experience insatiable hunger due to a dysfunction in the hypothalamus that regulates appetite, resulting in obesity when not properly managed.

This condition is a complex genetic disorder that affects multiple systems in the body, but the hallmark features of hypotonia and the drive for excessive eating are critical to its diagnosis and management. Other symptoms may include cognitive challenges and behavioral issues, but the prominent features centered around muscle tone and weight gain are what primarily define Prader-Willi syndrome.