Omenn syndrome

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Omenn syndrome is an autosomal recessive severe combined immunodeficiency associated with hypomorphic missense mutations in immunologically relevant genes of T-cells (and B-cells) such as recombination activating genes (RAG1 and RAG2), IL-7 Receptor ? gene (IL7R?), DCLRE1C-Artemis, RMRP-CHH, DNA-Ligase IV, common gamma chain, WHN-FOXN1, ZAP-70 and complete DiGeorge anomaly (DiGeorge Syndrome; CHARGE).

Video Omenn syndrome

Symptoms

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.

A characteristic symptom is chronic inflammation of the skin, which appears as a red rash (early onset erythroderma). Other symptoms include eosinophilia, failure to thrive, swollen lymph nodes, swollen spleen, diarrhea, enlarged liver, low immunoglobulin levels (except immunoglobulin E, which is elevated), low T cell levels, and no B cells.

Maps Omenn syndrome

Genetics

Omenn syndrome is caused by a partial loss of RAG gene function and leads to symptoms similar to severe combined immunodeficiency syndrome, including opportunistic infections. The RAG genes are essential for gene recombination in the T-cell receptor and B-cell receptor, and loss of this ability means that the immune system has difficulty recognizing specific pathogens. Omenn Syndrome is characterised by the loss of T-cell function, leading to engraftment of maternal lymphocytes in the foetus and the co-existence of clonally expanded autologous and transplacental-acquired maternal lymphocytes. Omenn syndrome can occasionally be caused in other recombination genes, including IL-7R? and RMRP.

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Diagnosis

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Treatment

The only treatment for Omenn syndrome is bone marrow transplantation. Without treatment, it is rapidly fatal in infancy.

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See also

• Purine nucleoside phosphorylase deficiency
• List of cutaneous conditions

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References

Source of the article : Wikipedia