Uniparental disomy (UPD) as the cause of inconsistencies in parentage tests: report of maternal UPD of chromosome 2 and review of the literature.

Uniparental disomy (UPD) is the abnormal situation in which both members of a chromosome pair exclusively comprise material of one of the parents. The incidence of UPD is estimated in 1:2000 live births. This rare condition is relevant for medical genetics due to imprinting disorders or recessive diseases; however, it may also impact for parentage testing, leading to apparent false parentage.