UPD

UPD is an acronym that can refer to several different concepts. The most widely used meaning in scientific literature is uniparental disomy, a genetic phenomenon in which both copies of a chromosome or part of a chromosome are inherited from a single parent rather than one copy from each parent.

In genetics, uniparental disomy (UPD) can be isodisomy, where two identical copies come from one parent, or heterodisomy, where the two different homologous chromosomes come from the same parent. UPD can arise through mechanisms such as trisomy rescue, monosomy rescue, or Gamete complementation, and it can occur for any chromosome. Clinically, UPD can disrupt genomic imprinting or increase homozygosity for recessive mutations, with implications for development and disease. Specific associations include maternal UPD of chromosome 15 and Prader-Will syndrome, and paternal UPD of chromosome 15 and Angelman syndrome, though UPD is a rare cause of these disorders relative to deletions. Detection typically involves genetic testing such as SNP microarrays and trio analysis, and may be complicated by mosaicism or segmental UPD.

Beyond genetics, UPD is used as an acronym in various contexts to denote organizations, policies, or documents whose full form depends on the field or institution. There is no single universal non-genetic meaning for UPD, so determining its meaning requires consulting contextual information.