ADA2 and hyperinsulinemic hypoglycemia, familial, 4: Deficiency of adenosine deaminase 2 (DADA2, OMIM 165,688) is an autosomal recessive autoinflammatory disease caused by biallelic loss-of-function variants in the ADA2 gene, formerly named CECR1 (cat eye syndrome chromosome region, candidate 1), located at chromosome 22q11.1 [1–3].