Immunological aspects of immunodeficiency diseases part 52

Hypomorphic mutations of RAG1 and RAG2 result in a leaky form of SCID called Omenn's syndrome. In Omenn's syndrome, a few T- and B-cell clones may be generated but the full T- and B-cell repertoire fails to develop. The few T- and B-cell clones that leak through may undergo secondary expansion. As a result, patients with Omenn's syndrome may not be markedly lymphopenic but the lymphocyte repertoire is oligoclonal and severe immunodeficiency is the outcome.