Prader-Willi syndrome and a bisatellited derivative of chromosome 15.

A de nova bistaellited derivative of chromosome 15, inv dup (15) (pter leads to q11 or 12::p11 or q11 or 12 leads to pter), was identified by multiple banding techniques in a patient with Prader-Willi syndrome. A comparison of familial no. 15 short arm polymorphisms indicated that the extra chromosome was the result of a non-sister chromatid exchange between the paternal no. 15 homologs prior to or during meiosis.