Understanding the genetic diagnosis behind Angelman syndrome

A test name matters. 'Genetic testing was normal' does not tell you whether methylation, copy-number changes, UBE3A sequence variants, UPD, or imprinting mechanisms were evaluated.

Review my genetic report

Diagram of chromosome 15q11-q13 showing the SNHG14 imprinting centre and UBE3A gene expression in maternal versus paternal inheritance

The appropriate sequence depends on the clinical situation and laboratory methods. This page is an educational overview, not a universal medical order.

Why one test may not answer every question

Different methods answer different questions. A normal result from one test does not rule out every Angelman mechanism. The report should state exactly which methods were used and which mechanisms were assessed.

Diagnostic pathway overview

Clinical suspicionMethylation-based testingMechanism clarificationUBE3A analysis where appropriateBroader differential testing when needed

Main molecular mechanisms

15q11.2–q13 deletion

A missing segment on the maternal copy of chromosome 15 that includes UBE3A.

UBE3A pathogenic variant

A sequence change within the UBE3A gene that reduces or removes function.

Paternal uniparental disomy (UPD)

Both copies of chromosome 15 are inherited from the father.

Imprinting defect

The maternal UBE3A gene is present but not properly activated.

What common methods detect

Method	Main question	Mechanisms commonly detected	Important limitations	Does it define the exact mechanism?
DNA methylation analysis	Is the maternal UBE3A region methylated/active?	Detects most deletions, UPD, and imprinting defects	May miss some UBE3A point variants; does not identify the exact mechanism in all cases	No — usually needs follow-up testing
MS-MLPA	Are copy-number and methylation patterns abnormal?	Deletions, some imprinting defects	May not detect all sequence variants or UPD without additional analysis	Can define deletion and some imprinting findings
Chromosomal microarray	Are there copy-number changes in the 15q region?	Large deletions and duplications	Does not detect methylation, UPD, or small sequence variants	Defines deletion size but not mechanism alone
FISH	Is a specific 15q region deleted?	Large deletions	Low resolution; does not detect methylation, UPD, or sequence variants	No — limited resolution
UBE3A sequencing	Are there sequence variants in UBE3A?	UBE3A pathogenic variants	May miss large intragenic deletions/duplications or methylation defects	Yes, when a pathogenic variant is identified
UBE3A deletion/duplication analysis	Are there intragenic copy-number changes?	UBE3A exon-level deletions or duplications	Does not detect point variants or methylation defects	Yes, when confirmed
UPD analysis	Are both chromosome 15 copies from one parent?	Paternal UPD	Does not detect deletions or sequence variants	Yes, when confirmed
Exome/genome sequencing	Are there variants in UBE3A or other genes?	UBE3A variants and Angelman-like differential diagnoses	May not detect methylation or imprinting defects; interpretation can be uncertain	Sometimes; depends on the finding

Not sure what your previous tests covered?

A genetic report review can map the methods used, the mechanisms assessed, and the questions that still need answers.

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