ADA2 and immune system disorder: Vasculitis, autoinflammation, immunodeficiency, and hematologic defects syndrome (VAIHS) or adenosine deaminase 2 deficiency (DADA2) is a rare autosomal recessive disease characterized by a highly variable clinical phenotype that is caused by bi‐allelic mutations in ADA2 (formerly known as Cat Eye Syndrome candidate region 1 or CECR1).1, 2