Do patients with maternal uniparental disomy for chromosome 7 have a distinct mild Silver-Russell phenotype?
A narrow segment of maternal uniparental disomy of chromosome 7q31-qter in SilverRussell syndrome delimits a candidate gene region.
Approximately 70% of PWS cases are associated with a de novo paternally derived deletion, ~25% with maternal uniparental disomy 15, and the rest with deletions or epimutations in the imprinting center or from chromosome 15q translocations (5-7).
Multiplex Percentages Causes of PWS PCR 60%-70% Deletion in paternally derived PWS region Yes 25%-30% Maternal uniparental disomy 15 (UPD) No <5% Chromosome translocation breaking within No the PWS critical region <5% Imprinting defect with variation No Methylation FISH Sequence Percentages MLPA PCR analysis analysis 60%-70% Yes Yes Yes No 25%-30% Yes Yes No No <5% No No Yes No <5% No No No Yes
2-q13 deletion on the paternally inherited chromosome 15, whereas 25% have maternal uniparental disomy
(UPD), <5% have an imprinting center sequence variant, and 1% have a structural chromosome rearrangement involving 15g11.
PWS results from loss of imprinted genes from the paternally inherited chromosome as a result of either interstitial deletion (-70% of cases) or maternal uniparental disomy
(UPD; -30% of cases) (1-4).