OBJECTIVETo enhance the knowledge of adenosine deaminase (ADA) deficiency associated severe combined immunodeficiency (SCID) with disseminated varicella infection after vaccination.

METHODSWith case report and review of literature, the background knowledge, clinical and laboratory findings, diagnosis and treatment of ADA-deficient SCID were discussed.

RESULTSThe patient had the condition with failure to thrive. The main complaint was more than three weeks of fever and rash. He had received the live attenuated Oka strain varicella vaccination approximately two weeks before the onset of rash. Varicella infection was confirmed with direct immunofluorescence assay. The patient had mild leukopenia, with 3% lymphocytes. The initial immunologic workup included decreased IgG, IgM and IgA, abnormal expanded lymphocyte enumeration which confirmed the reduction of CD3, CD4, CD8, CD19 and CD56. Enzyme testing for ADA activity showed remarkably low level in the hemolysate, as well as increased levels of deoxyadenosine nucleotides.

CONCLUSIONADA-deficient SCID has some characteristic clinical and laboratory findings. Management options for ADA-deficient SCID include hematopoietic stem cell transplantation, enzyme replacement therapy and gene therapy. Immunodeficiency should be considered in children with severe failure-to-thrive. Live vaccine administration should be avoided in patients with immunodeficiency.