Gene components of HLA class I includes –
**Core Concept**
HLA (Human Leukocyte Antigen) class I molecules are crucial for the immune system to recognize and eliminate infected cells or tumor cells. They are composed of three main components: α1, α2, and α3 domains, which are encoded by different genes.
**Why the Correct Answer is Right**
The α1 and α2 domains of HLA class I molecules are encoded by the _HLA-A_, _HLA-B_, and _HLA-C_ genes, which are located on the short arm of chromosome 6. These genes are highly polymorphic, meaning they have many different alleles. The α3 domain is encoded by the _HLA-A_, _HLA-B_, and _HLA-C_ genes as well, but it is less polymorphic than the α1 and α2 domains. The HLA class I molecules are expressed on the surface of almost all nucleated cells and play a key role in the immune response.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not a correct component of the HLA class I molecule.
**Option B:** This option is not a correct component of the HLA class I molecule.
**Option D:** This option is not a correct component of the HLA class I molecule.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that HLA class I molecules are crucial for the immune system to recognize and eliminate infected cells or tumor cells. Understanding the genetic components of HLA class I molecules is vital for understanding the immune response and the development of immunological disorders.
**Correct Answer: C. HLA-A, HLA-B, and HLA-C genes.**