Multiple terms for a complex phenotype: contribution of two clinical cases for the recognition of 22q11.2 deletion syndrome

22q11.2 microdeletion is the most common microdeletion syndrome in humans and occurs with a frequency of 1 in 2,000-6,000 live births. Its main clinical features are associated with a failure to form derivatives of the third and fourth branchial arches during embryonic development. The phenotype includes heart outflow tract defects, craniofacial dysmorphisms (prominent and bulbous tip, external ears malformations, and posterior cleft palate) and endocrinological and immune system dysfunctions, as well as neurological and psychiatric disorders. Patients with this syndrome received different names, such as DiGeorge syndrome and velocardiofacial syndrome, since the recognition was based on the phenotype. Recently, molecular and genomic techniques have shown that this syndrome has great phenotypic heterogeneity. Two children with quite distinct phenotypes from this microdeletion syndrome are described in order to review the most common clinical manifestations and highlight that the great clinical heterogeneity can complicate its recognition by pediatricians.