ADA2 Gene

The ADA2 gene (ADA2 stands for "adenosine deaminase 2") is a protein-coding gene located on chromosome 22q11.1. The protein encoded by the ADA2 gene is one of two adenosine deaminases found in humans that regulate levels of the signaling molecule adenosine. The enzyme adenosine deaminase, contributes to the degradation of extracellular adenosine, a signaling molecule that controls a variety of cellular responses. ADA2 is highly expressed in myeloid cells and plays a role in macrophage differentiation; however, its function remains largely unclear. Deficiency of ADA2 is associated with an imbalance in the differentiation of monocytes into proinflammatory M1 macrophages.

Diseases associated with ADA2 variations include:

• Sneddon syndrome
• and
• vasculitis, autoinflammation, immunodeficiency and hematologic defect syndrome (first manifestation in infancy and toddlerhood) is a PAN-like form. Zhou et al. (2014) verified homozygous or compound heterozygous mutations in the ADA2 and CECR1 genes (607575.0001-607575.0006). All but 1 mutation were missense mutations.

Deficiency of ADA2 (DADA2) is the first molecularly described monogenic vasculitis syndrome. Over 60 disease-associated mutations have been identified in all domains of ADA2, affecting catalytic activity, protein dimerization, and secretion. Vasculopathies ranging from livedo reticularis to polyarteritis nodosa (PAN) and life-threatening ischemic and/or hemorrhagic strokes dominate the clinical features of DADA2 (Meyts I et al. 2018).

1. Lee PY (2018) Vasculopathy, immunodeficiency, and bone marrow failure: the intriguing syndrome caused by deficiency of adenosine deaminase 2. Front Pediat 6: 282.
2. Meyts I et al (2018) Deficiency of adenosine deaminase 2 (DADA2): updates on the phenotype, genetics, pathogenesis, and treatment. J Clin Immunol 38:569-578.
3. Navon Elkan P et al (2014) Mutant adenosine deaminase 2 in a polyarteritis nodosa vasculopathy. New Eng J Med 370: 921-931.
4. Van Eyck L et al (2014) Mutant ADA2 in vasculopathies. (Letter) New Eng J Med 371: 478-479.
5. Van Eyck L et al (2014) Mutant ADA2 in vasculopathies. (Letter) New Eng J Med 371: 480.
6. Zhou Q et al (2014) Early-onset stroke and vasculopathy associated with mutations in ADA2. New Eng J Med 370: 911-920.