Prader-Willi syndrome

Definition:

A disease characterized by obesity, decreased muscle tone, decreased mental capacity, and hypogonadism.

Causes, incidence, and risk factors:

The exact cause of Prader-Willi is not understood. It is believed to be a chromosomal defect that resides on chromosome 15, but this has yet to be completely substantiated. The condition appears sporadically in families.

Signs of Prader-Willi may be seen at birth. New infants are often small and very floppy (hypotonic). Male infants may have undescended testicles. The growing child exhibits slow mental and delayed motor development, increasing obesity, and characteristically small hands and feet. Rapid weight gain may occur during the first few years as patient develops uncontrollable hunger and continue until the child develops morbid obesity.

Mental development is slow and the IQ seldom exceeds 80. Children with Prader-Willi generally are very happy, smiling, and pleasant to be around.

Affected children have an intense craving for food and will do almost anything to get it. This results in uncontrollable weight gain. Morbid obesity (the degree of obesity that seriously affects health) may lead to respiratory failure with hypoxia (low blood oxygen levels), cor pulmonale (right-sided heart failure), and death.