Microdeletions are genetic conditions caused by the loss of a part of a chromosome. Microdeletions are characterized by congenital abnormalities and intellectual impairment. The severity of the symptoms varies depending on the size and location of the microdeletion. The most common microdeletion syndrome is DiGeorge syndrome which occurs approximately once in 1000 pregnancies. The prevalence of DiGeorge syndrome increases to 1 in 100 in pregnancies with major structural anomalies such as congenital heart disease.