This one has been known to show up in many different forms in the USMLE Step 1 exams, so it’s no wonder it’s a favorite amongst test takers.
For starters, the 22q11 Microdeletion Syndromes are genetic disorders caused by a microdeletion at the 22q11 chromosome i.e a small part on the 22nd chromosome gets deleted. It mainly encompasses 2 syndromes- DiGeorge syndrome and Velocardiofacial syndrome.
DiGeorge syndrome occurs due to defects that take place during the development process of the third and fourth branchial arches. It manifests with thymic hypoplasia, parathyroid gland hypoplasia and cardiac abnormalities such as Truncus Arteriosus and Tetralogy of Fallot. Hypocalcemia (low calcium levels in the blood) also occurs as a result of hypoplasia of the parathyroid glands.
Velocardiofacial syndrome, being quite similar to DiGeorge syndrome, usually presents with palate, cardiac and facial abnormalities such as retrognathia and a long face with a relatively prominent nose.
So here’s a popular mnemonic to remember the 22q11 microdeletion syndromes.