Angelman syndrome (AS) is a genetic condition that causes severe mental retardation , severe speech impairment, and a characteristic happy and excitable demeanor.
Individuals with AS show evidence of delayed development by 6–12 months of age. Eventually, this delay is recognized as severe mental retardation. Unlike some genetic conditions causing severe mental retardation, AS is
not associated with developmental regression (loss of previously attained developmental milestones).
Severe speech impairment is a striking feature of AS. Speech is almost always limited to a few words. However, receptive language skills (listening to and understanding the speech of others) and non-verbal communication are not as severely affected.
Individuals with AS have a balance disorder, causing unstable and jerky movements. This typically includes gait ataxia (a slow, unbalanced way of walking) and tremulous movements of the limbs.
AS is also associated with a unique "happy" behavior, which may be the best-known feature of the condition. This may include frequent laughter or smiling, often with no apparent stimulus. Children with AS often appear happy, excited, and active. They may also sometimes flap their hands repeatedly. Generally, they have a short attention span. These characteristic behaviors led to the original name of this condition, the "Happy Puppet" syndrome. However, this name is no longer used as it is considered insensitive to AS individuals and their families.
AS has been reported in individuals of diverse ethnic backgrounds. The incidence of the condition is estimated at 1/10,000 to 1/30,000.
Causes and symptoms
Most cases of AS have been traced to specific genetic defects on chromosomes received from the mother. In about 8% of individuals with AS, no genetic cause can be identified. This may reflect misdiagnosis, or the presence of additional, unrecognized mechanisms leading to AS.
The first abnormalities noted in an infant with AS are often delays in motor milestones (those related to physical skills, such as sitting up or walking), muscular hypotonia (poor muscle tone), and speech impairment. Some infants seem unaccountably happy and may exhibit fits of laughter. By age 12 months, 50% of infants with AS have microcephaly (a small head size). Tremulous movements are often noted during the first year of life.
Seizures occur in 80% of children with AS, usually by three years of age. No major brain lesions are typically seen on cranial imaging studies.
The achievement of walking is delayed, usually occurring between two-and-a-half and six years of age. The child with AS typically exhibits a jerky, stiff gait, often with uplifted and bent arms. About 10% of individuals with AS do not walk. Additionally, children may have drooling, protrusion of the tongue, hyperactivity, and a short attention span.
Many children have a decreased need for sleep and abnormal sleep/wake cycles. This problem may emerge in infancy and persist throughout childhood. Upon awakening at night, children may become very active and destructive to bedroom surroundings.
The language impairment associated with AS is severe. Most children with AS fail to learn appropriate and consistent use of more than a few words. Receptive language skills are less severely affected. Older children and adults are able to communicate by using gestures or communication boards (special devices bearing visual symbols corresponding to commonly used expressions or words).
Some individuals with AS may have a lighter skin complexion than would be expected given their family background.
The clinical diagnosis of AS is made on the basis of physical examination and medical and developmental history. Confirmation requires specialized laboratory testing.
There is no single laboratory test that can identify all cases of AS. Several different tests may be performed to look for the various genetic causes of AS. When positive, these tests are considered diagnostic for AS. These include DNA methylation studies, UBE3A mutation analysis, and fluorescent in situ hybridization (FISH).
Children with Angelman syndrome will need help from a variety of professionals, including a general pediatrician and pediatric neurologist . A child psychiatrist and/or psychologist may be helpful as well, particularly to help design and implement various behavioral plans. Physical, occupational, and speech and language therapists may help support specific deficits. A learning specialist may be consulted for help with an individualized educational plan.
There is no specific treatment for AS. A variety of symptomatic management strategies may be offered for hyperactivity, seizures, mental retardation, speech impairment, and other medical problems.
The typical hyperactivity in AS may not respond to traditional behavior modification strategies. Children with AS may have a decreased need for sleep and a tendency to awaken during the night. Drug therapy may be prescribed to counteract hyperactivity or aid sleep. Most families make special accommodations for their child by providing a safe yet confining environment.
Seizures in AS are usually controllable with one or more anti-seizure medications. In some individuals with severe seizures, dietary manipulations may be tried in combination with medication.
Individuals with AS may be more likely to develop particular medical problems which are treated accordingly. Newborn babies may have difficulty feeding and special bottle nipples or other interventions may be necessary. Gastroesophageal reflux (heartburn) may lead to vomiting or poor weight gain and may be treated with drugs or surgery. Constipation is a frequent problem and is treated with laxative medications. Many individuals with AS have strabismus (crossed eyes), which may require surgical correction. Orthopedic problems, such as tightening of tendons or scoliosis, are common. These problems may be treated with physical therapy, bracing, or surgery.
Individuals with AS have significant mental retardation and speech impairment that are considered to occur in all cases. However, they do have capacity to learn and should receive appropriate educational training.
Young people with AS typically have good physical health aside from seizures. Although life span data are not available, the life span of people with AS is expected to be normal.
Children with AS appear to benefit from targeted educational training. Physical and occupational therapy may improve the disordered, unbalanced movements typical of AS. Children with a severe balance disorder may require special supportive chairs. Speech therapy is often directed towards the development of nonverbal communication strategies, such as picture cards, communication boards, or basic signing gestures.
The most pressing long-term concern for patients with AS is working out a life plan for ongoing care, since many are likely to outlive their parents. The parents of a child diagnosed with AS should consult an estate planner, an attorney, and a certified public accountant (CPA) in order to draft a life plan and letter of intent. A letter of intent is not a legally binding document, but it gives the patient's siblings and other relatives or caregivers necessary information on providing for her in the future. The attorney can help the parents decide about such matters as guardianship as well as guide them through the legal process of appointing a guardian, which varies from state to state.
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Jennifer Ann Roggenbuck, MS, CGC
Rosalyn Carson-Dewitt, MD
"Angelman Syndrome." Gale Encyclopedia of Neurological Disorders. . Encyclopedia.com. (April 21, 2018). http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/angelman-syndrome
"Angelman Syndrome." Gale Encyclopedia of Neurological Disorders. . Retrieved April 21, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/angelman-syndrome
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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.
Most children with Angelman syndrome are severely developmentally delayed. They never acquire normal speech, and they require care and supervision throughout their lives.
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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Rosalyn Carson-DeWitt, MD
"Angelman's Syndrome." Gale Encyclopedia of Children's Health: Infancy through Adolescence. . Encyclopedia.com. (April 21, 2018). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/angelmans-syndrome
"Angelman's Syndrome." Gale Encyclopedia of Children's Health: Infancy through Adolescence. . Retrieved April 21, 2018 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/angelmans-syndrome
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"Angelman syndrome." A Dictionary of Nursing. . Encyclopedia.com. (April 21, 2018). http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/angelman-syndrome
"Angelman syndrome." A Dictionary of Nursing. . Retrieved April 21, 2018 from Encyclopedia.com: http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/angelman-syndrome