Omenn syndrome

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Omenn syndrome
Classification and external resources
ICD-10 D81.2 (ILDS D81.210)
OMIM 603554
DiseasesDB 32676
eMedicine ped/1640

Omenn syndrome is an autosomal recessive severe combined immunodeficiency[1] associated with hypomorphic missense mutations in the recombination activating genes (RAG1 and RAG2), affecting circulating levels of both B-cells and T-cells.

Symptoms[edit]

Redness and scaliness of the entire skin on a 5-month-old female infant
A 5-month-old female infant with Omenn syndrome; she has red, scaly skin all over her body.

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[2] (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.[3]

Genetics[edit]

Omenn syndrome has an autosomal recessive pattern of inheritance.

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 difficult recognizing specific pathogens.[2]

Omenn syndrome can occasionally be caused in other recombination genes, including IL-7Rα and RMRP.[3]

Treatment[edit]

The only treatment for Omenn syndrome is bone marrow transplantation. Without treatment, it is rapidly fatal in infancy.[2] The disease can be cured by bone marrow transplantation.[3]

See also[edit]

References[edit]

  1. ^ Santagata S, Villa A, Sobacchi C, Cortes P, Vezzoni P (2000). "The genetic and biochemical basis of Omenn syndrome". Immunol Rev. 178: 64–74. doi:10.1034/j.1600-065X.2000.17818.x. PMID 11213808. 
  2. ^ a b c Parham, Peter (2009). The Immune System (3rd ed.). Taylor & Francis Group. ISBN 9781136977107. 
  3. ^ a b c Geha, Raif; Notarangelo, Luigi (2012). Case Studies in Immunology: A Clinical Companion (6th ed.). Garland Science. ISBN 978-0-8153-4441-4.