Angelman Syndrome is found in 1 of 10,000 births. It is a micro deletion syndrome affecting chromosome 15 (thanks to http://www.cureangelman.org/ for this image) involves a process of genomic imprinting where a sequence of genes from the maternal chromosome are silencing the critical corresponding genes from the fathers chromosome so that the end result is a defective chromosomal gene sequence in that region. This interferes with the fetal development and results in a series of changes in the person born with this chromosomal abnormality. The mirror image micro deletion syndrome of Angelman Syndrome is the Prader Willi syndrome, where the deletion of 15q11-q13 is paternally derived.
Signs and symptoms
In the case of Angelman syndrome there is a small head (microcephaly) and the individuals have mental retardation. Here is an image of a child with Angelman syndrome (thanks to www.primehealthchannel.com for this image).
Their movements are puppet-like, but not truly ataxic. A person with Angelman syndrome will frequently burst out in uncontrollable laughter. Seizures are also common and EEG recordings between seizures will show a characteristic pattern of bifrontal runs of notched slow waves. Sleep EEG’s show slow and sharp waves. The brain has normally folded surfaces (normal gyral development), but a mildly thinned grey matter layer (brain atrophy). The cerebellum shows marked atrophy.
As this is a genetic syndrome, there is at present no treatment available. These individuals will need to live in a supportive environment and often end up in a specialized home that is equipped to deal with these patients.
1. Cerebral Palsy due to Chromosomal Anomalies and Continuous Gene Syndromes: Clinics in Perinatology – Volume 33, Issue 2 (June 2006) – Copyright © 2006 W. B. Saunders Company
2. Behrman: Nelson Textbook of Pediatrics, 17th ed., © 2004 Saunders: Chapter 70 – Chromosomal Clinical Abnormalities