Reply #8: Thank you! [View All]

[Ilsa]

You just expanded my horizons quite a bit:

"In 1981, the Prader-Willi syndrome was found to be associated with a very small deletion in the long arm of human chromosome 15, between bands q11 and q13 (Ledbetter et al., 1981). However, in 1987, an identical deletion was reported in a number of patients who suffered from a very different disease, Angelman syndrome. These syndromes give quite distinct phenotypes (Figure 1). Prader-Willi syndrome is characterized by developmental delay, cryptorchidism (small or undescended testes), hyperphagia obesity (fatness due to overeating in an attempt to reach satiety), short stature, and mild retardation. Angelman syndrome is characterized by seizures, severe mental retardation, inappropriate laughter, and a characteristic face that is small with a large mouth and prominent chin.

The resolution to the paradox of two different syndromes caused by the same chromosomal deletion came in 1989 when it was discovered the Prader-Willi syndrome was always caused by defects involving the paternally derived chromosome, while Angelman syndrome was always caused by deletions in the maternally derived chromosome (Knoll et al., 1989). "

I found this online at http://zygote.swarthmore.edu/chrom3a.html