Angelman syndrome is a genetic disorder that affects the nervous system and causes intellectual and physical disabilities. It develops in infants right after conception, due to the malfunction or absence of the UBE3A gene that is inherited from the child’s mother.
Affected children can show symptoms of Angelman syndrome as young as six to 12 months, but most patients are diagnosed between the ages of 18 months and 6 years. Symptoms can be confused with autism or cerebral palsy, which are more prevalent than Angelman syndrome.
Distinctive physical features
The physical features vary among patients, and different patients have unique combinations of physical indicators. However, the most common physical indicator of Angelman syndrome seen in approximately 80 percent of patients is a smaller than normal head circumference, known as microcephaly. Some children also develop a flat occiput, which is the bone that makes up the back of the skull, as their skull ossifies.
Patients may have a wide smile with gaps between their teeth, coarse facial features, and a pale complexion with light-colored hair, known as hypopigmentation. Scoliosis or curvature of the spine is also common in Angelman syndrome.
Patients and especially children with Angelman syndrome are easily excitable and frequently laugh, smile, and gesture with animated hand flapping movements for no apparent reason and more often than most children.
Additional, less common symptoms include crossed eyes, involuntary eye movements known as nystagmus, sensitivity to heat, and an unusual fascination with water.
Movement and coordination issues
More than 95 percent of Angelman syndrome patients develop movement and balance disorders, specifically ataxia and unsteady and jerky movement of limbs. Seizures occur in more than 80 percent of patients before age 3. The development of motor skills in children is significantly delayed. In certain advanced cases, patients may not learn to walk until age 10.
Feeding problems during infancy can be attributed to sucking and swallowing issues and tongue thrusting and protrusion, which are characteristic of Angelman syndrome. Uncontrolled drooling is also common.
Issues with communication begin to be apparent when the baby is around six months old. The majority of affected babies do not start to babble until after their first birthday. Most patients continue to have limited speech or no speech capabilities throughout their lives; however, receptive and nonverbal communication aptitudes are higher than verbal skills. Adults with Angelman syndrome can typically communicate through gesturing or with the use of communication boards.
Although the majority of symptoms and other illnesses associated with Angelman syndrome typically remain for the patient’s life, which is on par with average life expectancies, a few symptoms have been documented as improving as patients age. These include:
- the tendency to need less sleep than other children or have issues falling and staying asleep;
- excitability, hyperactivity, and short attention span.
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