A variant of SCID with specific immune responses and predominance of gamma delta T cells.

[omenn syndrome]

We describe here a patient with a clinical and molecular diagnosis of recombinase activating gene 1 -deficient (RAG 1 -deficient ) SCID , who produced specific antibodies despite minimal B cell numbers . Memory B cells were detected and antibodies were produced not only against some vaccines and infections , but also against autoantigens . The patient had severely reduced levels of oligoclonal T cells expressing the alphabeta TCR but surprisingly normal numbers of T cells expressing the gammadelta TCR . Analysis at a clonal level and TCR complementarity-determining region-3 spectratyping for gammadelta T cells revealed a diversified oligoclonal repertoire with predominance of cells expressing a gamma 4 -delta 3 TCR . Several gammadelta T cell clones displayed reactivity against CMV-infected cells . These observations are compatible with 2 non-mutually exclusive explanations for the gammadelta T cell predominance : a developmental advantage and infection-triggered , antigen-driven peripheral expansion . The patient carried the homozygous hypomorphic R 561 H RAG 1 mutation leading to reduced V (D )J recombination but lacked all clinical features characteristic of Omenn syndrome . This report describes a new phenotype of RAG deficiency and shows that the ability to form specific antibodies does not exclude the diagnosis of SCID .

Diseases
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Diseases presenting "infection-triggered" symptom

omenn syndrome

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