Angelman syndrome

Angelman syndrome is a neurodevelopmental disorder usually caused by loss of function of the maternally inherited UBE3A gene. It commonly involves developmental delay, severe speech impairment, movement difficulties, and a distinctive behavioral profile.

UBE3A: UBE3A is a gene encoding an ubiquitin ligase that helps regulate protein turnover and neuronal function. Loss of functional UBE3A in neurons is the most common molecular basis of Angelman syndrome.
Chromosome 15: Chromosome 15 is one of the 23 pairs of human chromosomes and contains the imprinted 15q11-q13 region. UBE3A and several neighboring imprinted genes lie in this chromosome region.
Methylation analysis: Methylation analysis measures chemical marks on DNA to identify parent-specific patterns at selected genomic regions. It detects most deletion, imprinting-defect, and uniparental-disomy cases, while not identifying every UBE3A variant.
Prader-Willi syndrome: Prader-Willi syndrome is an imprinting disorder usually caused by loss of paternally expressed genes in chromosome 15q11-q13. It involves the same imprinted region but typically reflects loss of paternal rather than maternal gene expression.
Antisense oligonucleotide: An antisense oligonucleotide is a short synthetic nucleic acid designed to bind a specific RNA sequence and alter its activity. Experimental approaches use these molecules to reduce UBE3A-ATS and reactivate paternal UBE3A.
Genomic imprinting: Genomic imprinting is parent-of-origin-dependent gene expression caused by epigenetic regulation. In many neurons, the paternal UBE3A copy is silenced, leaving the maternal copy active.
DNA methylation: DNA methylation is the addition of methyl groups to DNA, often affecting gene expression. Methylation testing can distinguish several chromosome 15 mechanisms associated with Angelman syndrome.
Chromosomal microarray: Chromosomal microarray detects gains and losses of DNA across the genome at higher resolution than a karyotype. It can identify the common 15q11-q13 deletion and define its size.
Phelan-McDermid syndrome: Phelan-McDermid syndrome is a neurodevelopmental disorder usually caused by loss or disruption of SHANK3 on chromosome 22. It can also involve severe speech impairment and developmental delay, but has a different genetic cause.
Gene therapy: Gene therapy aims to treat disease by delivering, replacing, or modifying genetic material in cells. UBE3A delivery is being studied as a way to restore gene function in affected neurons.

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