Autism-World

In the majority of families there is only one individual affected by Angelman syndrome. In these families the affected person usually has a piece of one of their chromosome 15s missing ( deletion ). Deletions can be detected down the microscope or by looking at a persons DNA, their genetic material using special techniques in the laboratory. In cases with a chromosome 15 the parents chromosome are usually absolutely normal. Neither parent is a carrier Angelman syndrome but the deletion in the child usually arises by chance on the chromosome 15 which came from the mother. If a similar deletion arises on the chromosome 15 which comes from the father, then a completely different condition called Prader-Willi syndrome results.

There have been a few families where Angelman syndrome has occurred in a brother or sister and in these cases, there is usually no detectable deletion. In rare cases one parent, usually the mother, does carry a small genetic abnormality on one chromosome which can give rise to a AS child. Because of this it is important for both parents to have their chromosomes checked. In the vast majority of families the recurrence risk of Angelman syndrome is low, especially if there is a deletion of chromosome 15 and the parents chromosomes are normal the genetic situation is complicated, however, and may be different in different families, so referral to a genetic counselling clinic is advised to discus the genetic situation in each family. At present there is no absolutely reliable prenatal diagnosis available for those families at high risk of recurrence, but but advances have been made in this area and there is a good chance that one will be available soon. The majority will be at low risk and a prenatal test may not be indicated except for reassurance. many parents opt to have an amniocentesis test in subsequent pregnancies and again, this is best discussed with your geneticist and / or obstetrician.

Technorati : Angelman syndrome

This entry was posted on Saturday, September 1st, 2007 at 3:49 pm and is filed under Angelman Syndrome.