DiGeorge syndrome… what a complicated condition for such a little area of a single chromosome being affected. The condition’s descriptive and preferred name is 22q11.2. This is called a microdeletion. Along with microduplications, microdeletions are collectively known as copy number variants. Copy number variants can lead to disease when the change in copy number of a dose-sensitive gene or genes disrupts the ability of the gene(s) to function and affects the amount of protein produced. Other examples of microdeletion syndromes include Prader- Willi, (which is a deletion on 15q), and Cri du chat syndrome which results from a microdeletion on 5p. In this episode, we will review the varied penetrance of DiGeorge syndrome and review its genetic basis. What are some suggestive features found on prenatal ultrasound? What are the associated abnormalities/phenotypes? And how is this condition managed after birth? And why is this also known as CATCH22. We will answer all of these questions, and more, in this episode.