Angelman Syndrome
Description
Angelman Syndrome is a rare genetic disorder that primarily affects the nervous system. It is characterized by a unique set of symptoms including developmental delays, intellectual disability, speech impairment, and movement disorders. This blog post delves into the intricacies of Angelman Syndrome, shedding light on its causes, inheritance patterns, diagnosis, and management strategies.
Genes Involved
The primary genetic cause of Angelman Syndrome is a deletion or mutation in the UBE3A gene. This gene provides instructions for making a protein essential for the proper function of the nervous system.
Recognizing the Signs and Symptoms
Recognizing Angelman Syndrome can be challenging as symptoms vary in severity and presentation. Common signs include:
- Developmental delays: Delayed milestones in walking, talking, and sitting.
- Intellectual disability: Varying levels of cognitive impairment.
- Speech impairment: Difficulty with language development and communication.
- Movement disorder: Jerky movements, ataxia (lack of coordination), and tremors.
- Seizures: A significant portion of individuals with Angelman Syndrome experience seizures.
- Happy demeanor: A characteristic feature often described as a "happy puppet" or "laughing" demeanor.
- Sleep disturbances: Difficulty sleeping and disrupted sleep patterns.
- Hypopigmentation: Light skin, hair, and eyes.
- Protruding tongue: A distinctive facial feature often present.
- Abnormal EEG: An electroencephalogram may reveal distinctive patterns associated with Angelman Syndrome.
Causes
Angelman Syndrome arises from genetic abnormalities that affect the UBE3A gene. The most common causes are:
- Deletion of the UBE3A gene: A portion of chromosome 15 is missing, including the UBE3A gene.
- Mutation in the UBE3A gene: A change in the UBE3A gene‘s DNA sequence disrupts its function.
- Maternal uniparental disomy (UPD): Both copies of chromosome 15 are inherited from the mother, resulting in a lack of the paternal UBE3A gene.
- Imprinting defects: An error in the process of imprinting, which regulates gene expression, affects the UBE3A gene.
Inheritance/recurrence risk
Angelman Syndrome can be inherited or occur spontaneously. If one parent has the syndrome, there is a 50% chance of their child inheriting the condition. However, in most cases, the condition arises spontaneously due to new genetic mutations. The risk of recurrence is generally low but depends on the specific genetic cause.
