Clinical comparison of 59 Prader-Willi patients with and without the 15(q12) deletion.

Fifty-nine patients with Prader-Willi syndrome (PWS) (including three blacks) were enrolled in a behavior modification program including dietary restriction, nutritional education for self-management of food intake, and exercise. Caloric intake for most patients was 700-800 calories per day. The average stay per patient was 5 weeks with a mean weight loss of 6.6 kg. Thirty-one patients (53%) had apparently normal chromosomes compared to 25 patients (42%) with apparent 15(q12) deletion. Three patients had other chromosome abnormalities including two with mosaicism for idic(15)(q11) and one with a de novo apparently balanced translocation t(8q;18q). There were no differences in manifestations or the effects of the behavior modification program between chromosomally normal and abnormal patients. However, the mean weight loss in the 59 PWS patients was less than would have been expected based on their calculated daily caloric requirements suggesting that PWS patients have reduced caloric needs per unit of body weight compared to normal individuals. Supporting this also was that weight maintenance could be accomplished with only 1000 calories per day on the average. In general, behavioral response to the modification program was successful in that tantrum responses, while not eliminated, were reduced in frequency and severity.