Question

HLA B27 allele has been identified in those at greater risk for all except this autoimmune disease. a. Alkylosing spondylitis b. Psoriatic arthritis c. Reiter's disease d. Crohn's disease

Short answer

Answer: d. Crohn's disease

Step-by-step solution

Understand HLA B27 allele

The HLA B27 allele is a specific variant of the human leukocyte antigen (HLA) B gene, which is found on chromosome 6. The HLA B gene is part of the major histocompatibility complex (MHC) class I molecules and plays an essential role in the immune system. Individuals with the HLA B27 allele have a higher risk of developing certain autoimmune diseases due to the immune system's abnormal response to self-proteins.

List the autoimmune diseases associated with the HLA B27 allele

Based on research and scientific literature, the HLA B27 allele has been associated with an increased risk for the following autoimmune diseases: 1. Ankylosing spondylitis 2. Psoriatic arthritis 3. Reiter's disease (also known as Reactive Arthritis)

Determine which autoimmune disease is not associated with the HLA B27 allele

From the list of autoimmune diseases given in the exercise, we can identify the one that is not associated with the HLA B27 allele by comparing it to the list of associated diseases we established in step 2. We can see that Crohn's disease is not part of the list from step 2.

Conclusion

Out of the given autoimmune diseases (a. Alkylosing spondylitis, b. Psoriatic arthritis, c. Reiter's disease, d. Crohn's disease), the autoimmune disease that is not associated with the HLA B27 allele is d. Crohn's disease.