**Core Concept**
HLA-B*1502 is a specific allele of the human leukocyte antigen (HLA) B gene, which plays a crucial role in the immune system. This allele is associated with an increased risk of severe cutaneous adverse reactions (SCARs) to certain drugs.

**Why the Correct Answer is Right**
HLA-B*1502 is particularly significant in the context of carbamazepine, an anticonvulsant and mood stabilizer. Individuals carrying this allele are at a higher risk of developing Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), severe skin disorders that can be life-threatening. The mechanism involves the presentation of carbamazepine to T cells through HLA-B*1502, leading to an abnormal immune response.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because HLA-B*1502 is not associated with an increased risk of HIV infection. While HLA alleles can influence susceptibility to certain infections, HLA-B*1502 is specifically linked to drug reactions.
**Option B:** This option is incorrect because HLA-B*1502 is not a marker for a specific type of cancer. While HLA alleles can affect cancer risk, HLA-B*1502 is primarily associated with severe cutaneous adverse reactions to certain drugs.
**Option C:** This option is incorrect because HLA-B*1502 is not a marker for a specific autoimmune disease. While HLA alleles can contribute to autoimmune disease susceptibility, HLA-B*1502 is specifically linked to drug reactions.

**Clinical Pearl / High-Yield Fact**
When prescribing carbamazepine or other medications that carry a risk of SCARs, it is essential to screen patients for the presence of HLA-B*1502. This can help identify individuals at increased risk and enable early intervention if a severe reaction occurs.

**Correct Answer: D. Carbamazepine-induced Stevens-Johnson syndrome/toxic epidermal necrolysis**