In PWS, obesity (defined as increased weight for age) does not begin until after infancy which is a time when poor feeding and slow weight gain are typical. Hundreds of genes have been identified that may play a role in weight gain and obesity. Children who have unexplained, significant obesity before the age of 5 years may have a different genetic cause for their obesity. Genetic does not mean “inherited” in this situation.
When obesity occurs after childhood, there is less chance that it is due to a rare genetic condition such as PWS. Family patterns and the environment are more likely to be the cause of high weight late in childhood or in adulthood.
When obesity occurs before age 5 years, or when a child has significant relentless hunger despite enough food to eat, a genetics evaluation should be considered to rule out PWS or other recognized genetic causes of obesity.
Rare genetic disorders which cause obesity in early childhood include those associated with the MC4R pathway, for example:
- POMC deficiency obesity
- LEPR deficiency obesity
- Leptin deficiency obesity
- Prader-Willi syndrome
Other genetic syndromes associated with obesity
- Alstrom syndrome
- Bardet-Biedl syndrome
- Cohen syndrome
- Fragile X syndrome
There is information about these rare disorders at geneticobesity.com
Tumors of the pituitary/hypothalamic region (brain) or severe head trauma
Brain tumors such as craniopharyngiomas can result in behaviors seen in PWS such as unrelenting hunger and subsequent obesity. These tumors and severe head traumas that injure parts of the brain can lead to excessive hunger. Children with pituitary tumors will have symptoms such as growth failure, thirst abnormalities, visual problems, and headaches, not just weight gain.
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Butler MG. Single gene and syndromic causes of obesity: Illustrative examples. Prog Mol Biol Transl Sci. 2016;140:1-45.
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regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read in this publication.
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