Uniparental Disomy - Pathophysiology

Pathophysiology

UPD can occur as a random event during the formation of egg or sperm cells or may happen in early fetal development. It can also occur during trisomic rescue.

• When the child receives two (different) homologous chromosomes (inherited from both grandparents) from one parent, this is called an heterodisomic UPD. Heterodisomy (heterozygous) indicates a meiosis I error.
• When the child receives two (identical) replica copies of a single homolog of a chromosome, this is called an isodisomic UPD. Isodisomy (homozygous) indicates either a meiosis II or postzygotic chromosomal duplication.