Disease Example (trisomy rescue)
Angelman syndrome

Angelman syndrome can be caused by paternal uniparental disomy of chromosome 15 resulting from trisomy rescue of a trisomy 15 zygote (either 47,XY+15 or 47,XX+15) in which the total number of chromosomes in the cell is reduced to 46,XX or 46,XY such that two paternal chromosomes 15 remain.

  Disease Example (trisomy rescue): Prader-Willi syndrome

Prader-Willi syndrome can be caused by maternal uniparental disomy of chromosome 15 resulting from trisomy rescue of a trisomy 15 zygote (either 47,XY+15 or 47,XX+15) in which the total number of chromosomes in the cell is reduced to 46,XX or 46,XY such that two maternal chromosomes 15 remain.

trisomy rescue

Some Clinical Implications

  • Not all cases of uniparental disomy lead to an abnormal phenotype, only those in which the chromosome involved has imprinted gene(s).
  • If prenatal diagnostic testing via chorionic villus sampling (CVS) reveals a trisomic cell line involving a chromosome known to have imprinted genes, and follow-up amniocentesis reveals normal fetal chromosomes, UPD testing for the trisomic chromosome should be considered to exclude the possibility that trisomy rescue restored the normal karyotype in the fetal cells, but in doing so, led to UPD.

Last revision: 5-3-03

Related Terms: aneuploidy; imprinting; post-zygotic event; trisomy; uniparental disomy; uniparental disomy study

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From: Illustrated Glossary

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Pagon RA, Adam MP, Ardinger HH, et al., editors.
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