Rare disorder
DR. MANJEET MEHTA
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Since the Angelman Syndrome has no standardised treatment, early diagnosis is essential.
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Angelman Syndrome (AS) is a rare neuro-genetic disorder named after an English paediatrician, Dr. Harry Angelman, who first described the syndrome in 1965. The disorder is caused by deletion or disruption of a certain gene or genes located on the lon
g arm (q) of chromosome 15.
Angelman Syndrome is a rare neurological genetic disorder in which children have unusually happy demeanour i.e. laugh frequently for almost any reason and whose jerky movements and flapping of the hands are similar to those of a marionette, or puppet; hence the name “Happy Puppet Syndrome”. This condition is characterised by a puppet-like gait, fits of laughter and characteristic facial features.
Facial features
Abnormalities of the head and facial (craniofacial) area may include: a small head (microcephaly), deeply set eyes (occipital depression). Peculiar open-mouthed faces marked by a large, wide mouth (macrostomia) an underdeveloped upper jaw (maxillary hypoplasia) and protruding lower jaw (mandibular prognathism), widely spaced teeth, and continuous tongue protrusion. Also present usually are skull and other abnormalities.
The most common age of diagnosis is between three and seven years when the characteristic behaviours and features become most evident. In the child in whom the diagnosis is suspected, a high resolution chromosome analysis is often first performed to insure that no other chromosome disorder is present, since features such as mental delay, microcephaly, or seizures can be seen in other chromosome abnormalities.
Concurrent with the chromosome test, a Fluorescent In-Situ Hybridization (FISH) analysis is usually ordered. The FISH test is far superior having highest specificity, more than all other diagnostic techniques presently offered. Results are available within three days which confirm the presence or absence of the concerned Microdeletion.
Treatment
There is no standard course of treatment for Angelman syndrome. Physical therapy and adaptive devices may help patients with jerky gait. Early language evaluation and intervention is often recommended. Anticonvulsant medications may be prescribed for epilepsy.
During infancy, feeding difficulties and abnormal sleep patterns are typically present. In addition, by early childhood, individuals with Angelman Syndrome have severe developmental delays; impaired control of voluntary movements, resulting in a stiff manner of walking with jerky arm movements; and characteristic positioning of the arms with flexion of the elbows and wrists.
Although affected individuals may be unable to speak, many gradually learn to communicate through other means, such as sign language. In addition, some may have enough receptive language development to understand simple commands.
Prognosis
The clinical features of Angelman syndrome alter with age. As adulthood approaches, hyperactivity and poor sleep patterns improve. The seizures decrease in frequency and often cease altogether and the EEG abnormalities are less obvious.
The final prognosis is a good survival rate but with mental delay or retardation, and physical problems such as balance and speech abnormalities. Patients may have improvement of symptoms with therapy.
But chances of complications, probable outcomes, prospects for recovery, recovery period, survival rates, death rates, and other outcome possibilities are, by their nature, unpredictable.
Symptoms
Other symptoms include various neurological disorders like mental retardation, movement disorders like ataxic gait, or complete inability to walk, muscle hypotonia, jerky movements, motor retardation, EEG abnormalities, episodes of uncontrolled electrical activity in the brain (seizures), and frequent infantile spasms.
They are easily provoked and show prolonged paroxysms of laughter. Affected children exhibit developmental delays with absence or near absence of speech.
Over a period of time the affected child can almost reach normalcy. This depends on the start of the therapy, severity of symptoms, personal responses and support system. Since this is not recognised by many, the primary responsibility is to create awareness.
The type of counselling required for those affected would be to inform the parents about the child’s condition, ways to cope and also recommend therapies available. In case the condition is detected at an early stage, counselling needs to be started early.
The writer is a Mumbai-based medical geneticist.
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