GENOTYPE-PHENOTYPE CORRELATION IN A SERIES OF 167 DELETION AND NONDELETION PATIENTS WITH PRADER-WILLI-SYNDROME

A total of 167 patients with Prader-Willi syndrome (PWS) was studied a t the clinical and molecular level. Diagnosis was confirmed by the PW7 1 methylation test. Quantitative Southern blot hybridizations with a p robe for the small nuclear ribonucleoprotein N were performed to disti nguish between patients with a deletion (116 patient or 69.5%) and pat ients without a deletion (51 patients or 30.5%). These two types of pa tients differed with respect to the presence of hypopigmentation, whic h was more frequent in patients with a deletion (52%) than in patients without (23%), and to average birth weight of females and males, whic h was lower in patients with a deletion than in patients without. Newb orns with PWS had a lower birth weight and length at term, but normal head circumference in comparison with a control group. This finding ai ds the identification of the neonatal phenotype. In addition, our data confirm an increased maternal age in the non-deletion group.