Table 2 Molecular defects and recurrence risks in AS.
From: Practice guidelines for the molecular analysis of Prader-Willi and Angelman syndromes
Genetic defect | Proportion of cases | Recurrence risk |
|---|---|---|
De novo deletion of 15q11-q13 on the maternal chromosome | 70-75% | <1% |
Paternal uniparental disomy (UPD) of chromosome 15 | 3-7% | <1% |
Imprinting defect (with an imprinting centre deletion excluded) | 2-3% | <1% |
Deletions of the imprinting centre | ≈ 10-15% of patients with an imprinting defect | Up to 50% (if present in mother) |
UBE3A mutation | ≈10% | 50% if present in mother |
No identifiable molecular abnormality | ≈10% | Unknown (up to 50%) |