PWS is a genetic disorder caused by errors or deletions of genes related to chromosomes 15. The exact mechanisms responsible for causing PWS are unknown, but the errors related to chromosome 15 impact the way genes are expressed, or how genes turn ‘on’ or ‘off’.
While the specific causes for the chromosomal errors remain unclear, research indicates that this happens for one of three reasons:
Paternal genes on chromosome 15 are missing
Errors or defects in paternal genes on Chromosome 15
Two copies of chromosome 15 from the mother are inherited by the child and no chromosome 15 from the father.
How PWS impacts the hypothalamus
The hypothalamus (the part of the brain which controls hunger and thirst and hormones related to growth and sexual development) does not function properly in people with PWS.
This disruption in functioning of the hypothalamus due to chromosome 15 defects results in the breaking down of functions and causes:
Lack of satiety
Under developed sex hormones
Affected emotional expression and sleep cycles and many more body functions