Diverse phenotypic and genotypic presentation of RAG1 mutations in two cases with SCID

Abstract

Severe combined immunodeficiencies (SCID) comprise a spectrum of genetic defects that involve both humoral and cellular immunities. Defects in recombinating activating gene 1 (RAG1), RAG2, Artemis, or LIG4 can disrupt V(D)J recombination. Defective V(D)J recombination of the T and B cell receptors is responsible for T(-)B(-)NK(+)SCID. Amorphic mutations in RAG1 and RAG2 cause T(-)B(-)NK(+)SCID, whereas hypomorphic mutations cause an immunodeficency characterized by oligoclonal expansion of TCRgammadelta T cells, severe CMV infection and autoimmunity. First patient is a typical T(-)B(-)NK(+)SCID with clinical and immunologic findings while the second is atypical with normal immunoglobulin levels, CD4 lymphopenia, elevated TCRgammadelta T cells, persistent CMV infection, and autoimmune hemolytic anemia. These cases are presented to emphasize that mutations in RAG1 gene may lead to a diverse spectrum of clinical and immunologic findings while hypomorphic mutations may be related with autoimmunity and refractory CMV infection during infancy.