Antigen-peptide-transporter 2 deficiency

= = Antigen-Peptide-Transporter 2 Deficiency == Antigen-peptide-transporter 2 deficiency, also known as TAP2 deficiency, is a rare genetic disorder that affects the immune system. It is characterized by a malfunction in the transport of antigenic peptides across the endoplasmic reticulum membrane, which is crucial for the proper functioning of the immune response.

Pathophysiology

The TAP2 protein is part of the transporter associated with antigen processing (TAP) complex, which plays a critical role in the Major Histocompatibility Complex (MHC) class I antigen presentation pathway. The TAP complex is responsible for transporting peptides from the cytosol into the endoplasmic reticulum, where they bind to MHC class I molecules. These peptide-MHC complexes are then transported to the cell surface, where they are recognized by CD8+ T cells. In TAP2 deficiency, mutations in the TAP2 gene lead to a dysfunctional TAP complex, resulting in impaired peptide transport and reduced surface expression of MHC class I molecules. This impairs the immune system's ability to recognize and respond to infected or malignant cells.

Clinical Features

Patients with TAP2 deficiency often present with recurrent bacterial infections, particularly of the respiratory tract. This is due to the impaired ability of the immune system to detect and eliminate pathogens. Other symptoms may include skin lesions and chronic lung disease.

Diagnosis

Diagnosis of TAP2 deficiency is typically made through genetic testing, which can identify mutations in the TAP2 gene. Immunological assays may also be used to assess the expression of MHC class I molecules on the surface of cells.

Treatment

There is currently no cure for TAP2 deficiency. Treatment is primarily supportive and focuses on managing infections and other complications. Prophylactic antibiotics and immunoglobulin replacement therapy may be used to reduce the frequency and severity of infections.

Research and Future Directions

Research into TAP2 deficiency is ongoing, with studies focusing on understanding the molecular mechanisms of the disorder and developing potential therapies. Gene therapy and other novel approaches are being explored as potential treatments.

See Also

• Major Histocompatibility Complex
• CD8+ T cells
• Genetic Disorders

NIH genetic and rare disease info

• NIH info on Antigen-peptide-transporter 2 deficiency

Antigen-peptide-transporter 2 deficiency is a rare disease.