Stromal and epithelial cell defects leading to thymic hypoplasia are evident in several human conditions, including 22q11.2DS, CHARGE syndrome (featuring coloboma, heart defects, atresia choanae, growth retardation, genital abnormalities, and ear abnormalities), nude/SCID (AR FOXN1 mutations), and diabetic embryopathies (22). Here, AR is linked to coloboma.