Prader-Willi Syndrome

SIR: Prader-Willi syndrome is a chromosomal disorder that was first described by Langdon Down 1 in 1887 and was reported by Prader et al. 2 in 1956. They reported a series of patients with mental retardation, obesity, and hypogonadism.

In 1981, Ledbetter et al. 3 identified deletions of genes in the proximal arm of the paternal chromosome 15. Loss of gene material at the maternal chromosome 15 results in Angleman Syndrome. This pattern of inheritance—when expression of a gene depends on whether it is inherited from the father or the mother—is called imprinting. 4

Prader-Willi syndrome is the first human disease attributed to genomic imprinting. 4 In the United States, rate of prevalence of the syndrome has been reported to be 1 in 16,000. 1 Differences in prevalence between racial groups, sex, and age have not been reported. 1 Although the syndrome is best known for its food-related characteristics, including hyperphagia and obesity due to decreased perception of satiety secondary to hypothalamic abnormalities, 6, 7 it also involves other non-food-related characteristics, such as cognitive dysfunction, academic weakness, and behavioral problems. 5, 7, 8

Some reports have noted that behavioral problems increase in adolescence and adulthood years because of growing psychosocial stresses. 9 Often, these maladaptive behaviors pose multiple challenges to the clinicians and heighten the stress of the patient’s family.