Omenn syndrome

autorecessive

Omenn syndrome is a rare, inherited immunodeficiency disorder characterized by severe combined immunodeficiency (SCID) with features of autoimmunity. It is named after the American pediatrician Gilbert Omenn, who first described the condition.

Presentation

Patients with Omenn syndrome typically present in early infancy with severe erythroderma, hepatosplenomegaly, lymphadenopathy, and chronic diarrhea. They also exhibit failure to thrive and recurrent, often life-threatening infections. The syndrome is associated with elevated levels of immunoglobulin E (IgE) and eosinophilia.

Pathophysiology

Omenn syndrome is caused by mutations in genes critical for the development and function of T cells and B cells. The most commonly affected genes are RAG1 and RAG2, which are essential for the recombination of antigen receptors on these cells. Mutations in these genes lead to a partial defect in V(D)J recombination, resulting in the production of autoreactive T cells and a lack of functional B cells.

Diagnosis

The diagnosis of Omenn syndrome is based on clinical presentation, laboratory findings, and genetic testing. Laboratory tests typically show elevated IgE levels, eosinophilia, and absent or low levels of circulating B cells. Genetic testing can confirm mutations in the RAG1 or RAG2 genes or other genes associated with SCID.

Treatment

The primary treatment for Omenn syndrome is hematopoietic stem cell transplantation (HSCT), which can restore normal immune function. Prior to transplantation, patients may require supportive care, including antibiotics, antifungals, and intravenous immunoglobulin (IVIG) to manage infections and other complications.

Prognosis

The prognosis for patients with Omenn syndrome has improved with advances in HSCT. Early diagnosis and treatment are critical for improving outcomes. Without treatment, the condition is usually fatal in early childhood due to severe infections and complications from autoimmunity.

See also

• Severe combined immunodeficiency
• Autoimmunity
• Hematopoietic stem cell transplantation
• Immunoglobulin E
• Eosinophilia

External links

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