ABSTRACT
Prader-Willi syndrome (PWS) is a complex disorder with cardinal features of infantile hypotonia (94% of subjects), mental deficiency (average IQ of 65, range 20-90; 97%), hypogonadism (95%), early onset of childhood obesity (94%), small hands and feet (83%), short stature (76%), and a characteristic facial appearance (e.g., narrow bifrontal diameter, almondshaped eyes, and a triangular mouth) (1). Prader-Willi syndrome is the most common genetic cause of marked obesity
in humans (1). It is estimated that there are 350,000-400,000 people with this syndrome worldwide with more than 4000 persons with PWS known to the Prader-Willi Syndrome Association (U.S.A.) out of an approximate 17,000-22,000 (2). Prader-Willi syndrome has an incidence of 1 in 8000-25,000 individuals (1,3). The population prevalence is estimated at 1-50,000 (4). Prader-Willi syndrome and Angelman syndrome, an entirely different clinical condition, were the first examples in humans of genomic imprinting. Genomic imprinting or the differential expression of genetic information depending on the parent of origin plays a significant role in other conditions including malignancies (5,6).
