Angelman Syndrome (AS) is a rare genetic and neurological disorder that mainly affects the nervous system of a person.

AS affects males and females. The disorder affects one in 10,000 to 20,000 individuals.
The symptoms of AS include sleep problems, seizures, small head, specific facial appearance, speaking problems, developmental disability and severe intellectual disability.
Children affected with AS generally have a happy personality and have particular interest in water. These symptoms generally become noticeable by one year of age. AS is typically developed due to a new mutation rather than one inherited from a person's parents.
AS is due to a lack of function of part of chromosome 15 inherited from a person's mother. Most of the time, it is due to a deletion or mutation of the UBE3A gene on that chromosome. Occasionally, it is due to inheriting two copies of chromosome 15 from a person's father and none from the mother.
As the father's versions are inactivated by a process known as genomic imprinting,  no functional version of the gene remains. Diagnosis is based on symptoms and possibly genetic testing.
No cure of AS is available till date. Treatment of this genetic disorder is generally supportive in nature. Anti-seizure medications  are used in those with seizures. Physical therapy and bracing may help with walking. Those affected have a nearly normal life expectancy.
AS is named after a British paediatrician, Harry Angelman,  who first described the syndrome in 1965. An older term, "Happy Puppet Syndrome", is generally considered pejorative.
Many cases may go undiagnosed making it difficult to determine the disorder’s prevalence in the general population.
A diagnosis of Angelman syndrome may be made based upon a detailed patient history, a thorough clinical evaluation and identification of characteristic findings.