Synonym: UPD

The situation in which both copies of a chromosome pair (or chromosome pair segment) are from one parent (i.e., no copy is from the other parent). The individual may have two identical copies of one of the pair of parental chromosomes (termed uniparental isodisomy), or may have one copy of each of the parental chromosome pair (termed uniparental heterodisomy). Uniparental disomy can result in an abnormal phenotype in some instances.

Related terms: imprinting; trisomy rescue; uniparental heterodisomy; uniparental isodisomy