Prader Willi syndrome

Abstract

Note The Prader Willi syndrome (PWS) is characterized by diminished fetal activity, dysmorphic facial features, small hands and feet, marked hypotonia, neonatal feeding problems, thick saliva, hyperphagia and weight gain between the ages of 1 and 6, poor linear growth, short stature, hypothalamic dysfunction (obesity, absence of satiety, hypogonadism with cryptorchidism, abnormal temperature control and GH deficiency), cognitive difficulties and characteristic behavioural traits. Inheritance It is sporadic and familial cases are rare. The incidence is 1:10.000-15.000 births. Etiology PWS is genetically heterogeneous. The absent expression of the paternal activity in the critical region on chromosome 15 has been found in patients with PWS. In 70-75% of patients there is a deletion of the paternal 15q11-q13 chromosome (del15) and in about 25% there is a maternal uniparental disomy 15 (UDP15), and a small percentage of patients may have an imprinting center mutation or translocations involving chromosome15. In the 15q11-q13 region a lot of candidate genes are present. The C/D box small nucleolar RNA (snoRNA) gene cluster HBII-85, IPW, PAR1, MAGEL2 and SNRPN genes is not expressed in patients with PWS and may be involved in the phenotype.