Angelman's syndrome is a relatively rare genetic disorder that causes a variety of neurological problems, including developmental delay, seizures, speech impairment, and problems with movement and balance.
Angelman's syndrome was first described in 1965 by Harold Angelman, who noted that a group of children in his medical practice had flat heads, made jerky movements, held their tongues in a protruding way, and had curious bouts of laughter.
Angelman's syndrome is relatively rare. As of the early 2000s there were only about 1,000 to 5,000 known cases of the syndrome in the United States. There is no predilection for either sex or for any particular ethnicity.
Causes and symptoms
Most cases of Angelman's syndrome can be traced to a genetic abnormality inherited from a maternal chromosome (15). A particular area of genes that should control the production and function of a protein called ubiquitin is either absent or ineffective. A minority of cases of Angelman's syndrome are due to new mutations in this same area of genes.
Children with Angelman's syndrome have an abnormally small, flat appearance to their skull. By one to two months of age, infants with the syndrome develop feeding difficulties. By six to 12 months, developmental delay is usually noted. Most children develop seizures by three years of age. Other characteristics of the syndrome include abnormally decreased muscle tone, fair skin and hair, protruding jaw, hyperactivity, episodes of uncontrollable laughter, difficulty sleeping, and severe problems with movement and balance. The disorder is sometimes called "happy puppet syndrome," because many children with the disorder have jerky, flapping movements of the arms; a stiff, jerky style of walking (gait); a happy, excited demeanor; and regular episodes of uncontrollable laughter.
Diagnosis is made by noting the characteristic cluster of symptoms. Careful chromosomal study can reveal abnormalities on chromosome 15 that are consistent with those identified in Angelman's syndrome.
As of 2004 there is no cure for Angelman's syndrome. Treatments attempt to ameliorate the symptoms in order to improve the quality of life. Treatments may include anti-seizure medications, physical and occupational therapy, and speech and language therapy.
Ataxia—A condition marked by impaired muscular coordination, most frequently resulting from disorders in the brain or spinal cord.
Developmental delay—The failure of a child to meet certain developmental milestones, such as sitting, walking, and talking, at the average age. Developmental delay may indicate a problem in development of the central nervous system.
There are no methods to prevent Angelman syndrome. However, if the disorder is known to run in a family, genetic counseling may help parents evaluate their level of risk for having a child with this disorder. Specialized testing of chromosome 15 will be required; the usual tests done during amniocentesis or chorionic villi sampling will not reveal the specific, small genetic flaw that causes Angelman syndrome.
Caring for a child with Angelman syndrome constitutes a complex challenge. Parents should be encouraged to seek out parental and sibling support groups and respite care in order to help them face these challenges.
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American Academy of Pediatrics. 141 Northwest Point Blvd., Elk Grove Village, IL 60007-1098. Web site: <www.aap.org>.
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Rosalyn Carson-DeWitt, MD