Angelman Syndrome (AS) is a rare neurogenetic disorder that affects the nervous system and causes severe developmental delay, motor impairment, absence of speech, and a characteristically happy demeanor. Children with AS often have frequent laughter, hand-flapping movements, and sleep disturbances.
Although symptoms appear in early infancy, diagnosis is often delayed until 1–4 years of age due to the nonspecific nature of early signs.
What Causes Angelman Syndrome?
Angelman Syndrome (AS) is caused by disruption of the UBE3A gene located on chromosome 15 (15q11-q13), which is active only on the maternal allele in certain brain regions. The UBE3A gene encodes an enzyme essential for neuronal function and synaptic development. In neurons, only the maternal copy is active; the paternal copy is epigenetically silenced. Loss of function of the maternal UBE3A gene results in impaired brain development, affecting learning, movement, and behavior. AS is a sporadic genetic condition, and most cases are not inherited. However, rare familial cases require genetic counseling.