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Omenn syndrome

The Omenn syndrome can be caused by mutations in the recombination activating the RAG1 (179615) and RAG2 (179616) genes on chromosome 11p and the Artemis gene (DCLRE1C; 605988) on chromosome 10p.
Omenn syndrome is an autosomal recessive form of severe combined immunodeficiency (SCID) characterized by erythroderma, desquamation, alopecia, chronic diarrhea, failure to thrive, lymphadenopathy, and hepatosplenomegaly. Patients develop fungal, bacterial, and viral infections typical of SCID. In this syndrome, the SCID is associated with the virtual absence of B cells and the presence of oligoclonal autoreactive T cells. Lymphocytosis results from the expansion of an oligoclonal population of activated and antigen-stimulated T helper 2 (TH 2) cells that produce elevated levels of interleukin 4 (IL-4) and interleukin 5 (IL-5). The latter cytokines mediate eosinophilia and elevated immunoglobulin E (IgE) levels. Omenn disease terminating in lymphoma.
The symptoms are very similar to graft-versus-host disease (GVHD). This is because the patients have some T cells with limited levels of recombination with the mutant RAG genes. These T cells are abnormal and have a very specific affinity for self antigens found in the thymus and in the periphery. Therefore, these T cells are auto-reactive and cause the GVHD phenotype.

OTHER NAME(S): RETICULOENDOTHELIOSIS, FAMILIAL, WITH EOSINOPHILIA
SEVERE COMBINED IMMUNODEFICIENCY WITH HYPEREOSINOPHILIA

TYPE: risk of malignant disease, skin problem, immunodeficiency

Related patway(s): non-homologous end-joining (NHEJ)

DNAtraffic protein(s) related to disease: DCLRE1C (Artemis)

OMIM: 603554

Last modification date: July 30, 2011