<unk>  or<unk> 's<unk>  (AS) is a genetic disorder that mainly affects the nervous system. Symptoms include a small head and a specific facial appearance, severe intellectual disability, developmental disability, limited to no functional speech, balance and movement problems, seizures, and sleep problems. Children usually have a happy personality and have a particular interest in water. The symptoms generally become noticeable by one year of age.<unk>  is due to a lack of function of part of chromosome 15, typically due to a new mutation rather than one inherited from a person's parents. 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 their 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 is available. Treatment 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 affects 1 in 12,000 to 20,000 people. Males and females are affected with equal frequency. It is named after British pediatrician Harry<unk> , who first described the<unk>  in 1965. An older term, happy puppet<unk> , is generally considered pejorative. Prader–Willi<unk>  is a separate condition, caused by a similar loss of the father's chromosome 15.
Angelman syndrome
Cerebral palsy
Gitelman syndrome
Prader–Willi syndrome
FG syndrome
Rett syndrome
Perlman syndrome
Autism spectrum