Dr. Joe Wagstaff, an associate professor of pediatrics at the University of Virginia, originally began his studies of Angelman syndrome at Children's Hospital in Boston before joining the staff at the University of Virginia. He says much of the interest in the genetics of Angelman syndrome stems from the fact that 70 percent of children who have Angelman syndrome have a piece missing from chromosome 15. Meanwhile, 70 percent of the individuals who have a completely different genetic syndrome called Prader-Willi also have the same deletion on chromosome 15.

"Around 1990, it was discovered the only difference between the genetics in Angelman syndrome and Prader-Willi syndrome was that if you had this particular deletion on the chromosome 15 from your mother you have Angelman syndrome," says Dr. Wagstaff. "If you get exactly the same deletion on the chromosome 15 from your father, you have Prader-Willi syndrome."

Children with Prader-Willi have mild developmental problems, obsessive behavior and obesity. "In the newborn period children with Prader-Willi are generally very, very, very hypertonic. They have very low muscle tone and almost always require some kind of assistance with feeding," Dr. Wagstaff says. "And then their muscle tone gradually improves, and when they are between 1 and 2 years of age, they shift into this overeating mode. People with Angelman syndrome from the beginning have some reduction in their head control but they have nowhere near the very severe low muscle tones that Prader-Willi kids have."

Dr. Wagstaff notes that there are four different genetic causes for Angelman syndrome, and essentially all the causes lead to lack of maternal copy of UBE3A in the brain. "As far as we know there is no association with mother's age, and we also have never been able to find any consistent association with any kind of exposures or dietary or medication or anything of that sort," he says.