RELATIONSHIP OF SLEEP ABNORMALITIES TO PATIENT GENOTYPES IN PRADER-WILLI-SYNDROME

To assess whether sleep abnormalities are related to the genetic abnor malities in Prader-Willi Syndrome (PWS), we performed polysomnographic studies (nighttime and daytime) and determined the chromosome 15 geno types in eight patients with PWS, Four patients demonstrated sleep ons et REM periods (SOREM), and five met the objective polysomnographic cr iteria for severe or moderate excessive daytime sleepiness (EDS). Thre e of the four patients with SOREM displayed a paternally derived delet ion of chromosome 15q11-q13, whereas the fourth exhibited maternal uni parental heterodisomy in this chromosomal region (UPD), Two of the fou r patients that did not display SOREM carried paternally derived delet ions; the remaining two demonstrated UPD. Pour of the five patients wi th EDS displayed paternal deletions, and the fifth exhibited UPD, One of three patients without evidence of EDS demonstrated paternal deleti on; the remaining two showed UPD. Although neither EDS nor SOREM was n ot consistently associated with a specific genetic abnormality, these phenotypes may be more common in patients with paternal deletions than in those with UPD, Sleep abnormalities in PWS cannot be explained by a single genetic model. (C) 1996 Wiley-Liss, Inc.