ABSTRACT
RAG mutations cause a spectrum of severe immunodeficiencies ranging from classical severe combined immunodeficiency( SCID) and Omenn syndrome to an increasing number of peculiar phenotypes. Based on the distinct levels of RAG expression in various patients, their immunophenotypes, histopathological findings and clinical manifestations are diverse. The subtypes of RAG-defect diseases have been described as classical SCID,SCID with maternal T cells,classical Omenn syndrome,atypical Omenn syndrome,granuloma-tous inflammation,predominance/expansion of γδ-T cells and maternal T-cell engraftment. The complete failure or partial blockage of lymphocyte development and differentiation can cause repeated infections with autoimmune reactions frequently,and may be lethal. Thorough assessment and interpretation of various phenotypes will guide accurate diagnosis,definitive treatment and the mechanism research.