Transplant Medicine

The Major Histocompatibility Complex (MHC) contains over 128 functional genes. This is the densest part of the human genome and is responsible for most autoimmune diseases. This region also determines vaccine responsiveness, adverse drug reactions, disease progression and transplant rejection. The MHC genes are multigenic with a high degree of allelic polymorphism. There are over 7,500 different alleles and over 5,458 expressed MHC antigens currently known. (DeFranco, Locksley & Robertson, 2007). Genomic evolution and HLA screening have been extremely profitable to Transplant Medicine.

A brief analysis of MHC variability reveals two classes of antigens belonging to this complex; class I (A, B, and C) and II (DR, DQ, and DP). Both classes of molecules are expressed in a co-dominant fashion. These molecules are designed to recognize antigens that are foreign to the body and present them to the T cells. (Janeway, Travers & Walport, 2001)

The co-dominant mode...
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