Novel Mutation in CECR1 Leads to Deficiency of ADA2 with Associated Neutropenia

Adenosine deaminase 2 (ADA2) have been reported to cause vasculitic diseases and immunodeficiency recently. Patients present with stroke episodes and rashes mimicking polyarteritis nodosa (PAN). We report a patient who has been followed up with severe neutropenia and found an unexpectedly revealed novel mutation in CECR1 affecting ADA2. We reviewed medical records and clinical history of the patient. No mutations in other known neutropenia genes such as ELA, G6PC3, HAX1, AP3B1, LAMTOR2, VPS13B, VPS45, GFI1, JAGN1, or WAS could be detected. Sanger sequencing was used to confirm the genetic variants in the patient and relatives. Genetic analysis by exome sequencing revealed a novel mutation in the gene CECR1 (c.G962A; p.G321E) which segregated perfectly in the relatives. This is the first DADA2 patient presenting with severe neutropenia. We suggest that in patients with unexplained cytopenias combined with immunodeficiency, fevers of unknown origin and high inflammation markers, DADA2 should be considered.