Angelman Syndrome

Definition

Angelman Syndrome is a genetic disorder characterized by severe intellectual disability, speech impairment, and problems with movement and balance, often accompanied by a happy demeanor and frequent laughter. This syndrome is primarily caused by the loss of function of the UBE3A gene on chromosome 15, which highlights the role of genomic imprinting, where the expression of genes depends on their parent of origin.

5 Must Know Facts For Your Next Test

1. Angelman Syndrome results from a deletion or mutation in the UBE3A gene that is normally expressed from the maternal allele, making this condition an example of genomic imprinting.
2. Individuals with Angelman Syndrome typically have a happy demeanor, frequent laughter, and developmental delays, particularly in speech and motor skills.
3. The syndrome can be diagnosed through genetic testing that identifies abnormalities in the UBE3A gene or through methylation analysis of chromosome 15.
4. Angelman Syndrome is often misdiagnosed as cerebral palsy or autism due to overlapping symptoms, but it has unique characteristics such as seizures and a specific gait pattern.
5. Current treatments focus on managing symptoms and improving quality of life through therapies like physical therapy, speech therapy, and medications for seizure control.

Review Questions

• How does Angelman Syndrome illustrate the concept of genomic imprinting?
  • Angelman Syndrome exemplifies genomic imprinting because it arises specifically from the loss of function of the UBE3A gene that is normally expressed only from the maternal allele. In cases where this gene is mutated or deleted from the mother’s chromosome 15, the paternal copy remains silent due to genomic imprinting. This means that individuals with this syndrome cannot express a functional UBE3A protein, leading to the symptoms associated with the disorder.
• Compare and contrast Angelman Syndrome with Prader-Willi Syndrome in terms of their genetic causes and clinical features.
  • Angelman Syndrome and Prader-Willi Syndrome are both linked to abnormalities on chromosome 15 but differ fundamentally in their genetic causes and clinical manifestations. Angelman Syndrome results from a loss of function in the maternal UBE3A gene, leading to symptoms such as severe intellectual disability and an ataxic gait. In contrast, Prader-Willi Syndrome occurs due to paternal gene deletion or uniparental disomy affecting different genes, resulting in obesity, hyperphagia, and developmental delays. Thus, while they share some similarities related to chromosome 15, their presentations and underlying genetic mechanisms are distinctly different.
• Evaluate the impact of early diagnosis and intervention on individuals with Angelman Syndrome.
  • Early diagnosis and intervention for individuals with Angelman Syndrome significantly improve their developmental outcomes and quality of life. By identifying the syndrome early through genetic testing, families can access tailored therapies such as physical therapy, speech therapy, and seizure management sooner. These interventions help address developmental delays and enhance communication skills, ultimately enabling individuals to reach their fullest potential. Moreover, understanding the condition allows families to better navigate care strategies and support resources effectively.

Related terms

UBE3A: A gene located on chromosome 15 that is critical for normal neurological development; its loss of function is linked to Angelman Syndrome.

Genomic Imprinting: A genetic phenomenon where only one allele of a gene is expressed depending on whether it is inherited from the mother or father.

Prader-Willi Syndrome: A genetic disorder also associated with chromosome 15, resulting from the loss of paternal gene expression, leading to obesity and intellectual disabilities, often contrasted with Angelman Syndrome.