Prader-Willi syndrome associated with inversion of chromosome 15

A boy with Prader-Willi syndrome was found to have an inversion of chromosome 15,[46,XY,inv(15)(p13q13)]. His unaffected father has an apparently identical inversion of chromosome 15 but in addition has a number 14 chromosome with double satellites. This report supports previous indications of a relationship between a "position effect" and the etiology of Prader-Willi syndrome. However, a more complicated explanation is required in view of the cytogenetic findings in the proband's father.