But what is Prader-Willi Syndrome?
Prader-Willi is caused by the deletion of a gene on chromosome 15. For unknown reasons, in normal development, only the father’s copy of this gene is active. The maternal copy of this gene is turned off in all people. When there is a deletion of this gene on that one paternal copy received, the disease occurs. This is because the child is left with only the maternal copy, which is inactive in all people.
Signs of Prader-Willi can be seen at birth. New infants with the condition are often small and very floppy (hypotonic). Baby boys may have undescended testicles. The growing child often exhibits slow mental and delayed motor development, increasing obesity and small hands and feet.
During the first few years of life, a child with Prader-Willi feels ravenously hungry. This leads to uncontrollable eating and subsequent obesity. Respiratory failure with hypoxia (low blood oxygen levels) and corpulmonale (right-sided heart failure) are also common. The child has slow mental development, and the IQ seldom exceeds 80.
Signs of Prader-Willi Syndrome
- Floppy new born infant (hypotonic)
- Small for gestational age
- Undescended testicles in baby boys
- Slow mental development
- Very small hands and feet in comparison to the body
- Delayed motor development
- Rapid weight gain with marked obesity
- Insatiable appetite, food craving
- Almond shaped eyes
- Narrow skull