Mosaic genome-wide maternal isodiploidy: an extreme form of imprinting disorder presenting as prenatal diagnostic challenge
1.5 Mutational spectrum 75% Maternal deletion 15q11–q13. 1–2% Paternal uniparental disomy (upd(15)pat). 3% Imprinting defect. 5–10% Variants in the UBE3A gene. 10–15% Unknown (It is important to exclude differential diagnoses in these cases as there is phenotypic overlap with several other genetic disorders). Data on this disease (gene variants/phenotype) can be found in the public database Decipher (https://decipher.sanger.ac.uk).