Angelman Syndrome (AS) is a rare neuro-genetic disorder that affects approximately 1 in 15,000 to 20,000 people worldwide. The primary cause of AS is a mutation or deletion of the maternal copy of the UBE3A gene, located on chromosome 15. This mutation or deletion can be caused by several different mechanisms, including uniparental disomy (UPD), a chromosomal abnormality, or a defect in the imprinting process.
The most common cause of Angelman Syndrome is a mutation or deletion of the maternal copy of the UBE3A gene, which is located on chromosome 15. This mutation or deletion can occur in a variety of ways, such as through a chromosomal abnormality, a defect in the imprinting process, or through uniparental disomy (UPD). UPD is an abnormality in which two chromosomes from the same parent are inherited instead of one from each parent. In the case of AS, this means that the child can inherit two copies of the chromosome 15 from the mother, resulting in the mutation or deletion of the maternal UBE3A gene.
The mutation or deletion of the UBE3A gene is the most common cause of Angelman Syndrome, but it is not the only cause. Other possible causes include mutations or deletions of other genes, such as UBE3B, GABRA3, and GABRB3, which are located on chromosomes 15, 7, and 15, respectively. Additionally, some cases of AS have been linked to imprinting defects, which are caused by a mutation or deletion of a specific DNA region that is responsible for setting imprinted expression of genes.