Clinical conditions known to impact these stromal cell populations are chromosome 22q11.2 deletion syndrome (22q11.2del), also referred to as DiGeorge syndrome, Coloboma-heart defects-atresia choanae-retardation of growth-genital abnormalities-ear (CHARGE) syndrome arising from mutations in Chromodomain Helicase DNA Binding Protein 7 (CHD7), Nude/SCID due to autosomal recessive mutations in Forkhead Box N1 (FOXN1), otofaciocervical syndrome type 2 (OTFCS2) due to mutations in PAX1, as well as mutations in TBX1 (located within the chromosome 22q11.2 locus) and TBX2 (Table 1) (9–17). This evidence concerns the gene PAX1 and 22q11.2 deletion syndrome.