Prevalence of HLA-B51 in the Normal Population
The prevalence of HLA-B51 in the normal population varies significantly by ethnicity, ranging from less than 1% in some African populations to 10-15% in Han Chinese populations. 1
Geographic and Ethnic Variation
- HLA-B51 prevalence shows marked geographic distribution that follows ancient trading routes, particularly the Silk Road, with higher prevalence in regions between the Mediterranean basin and East Asia 2
- In Caucasian populations, HLA-B51 prevalence is approximately 5-8% 1
- In African and Asian populations, prevalence is generally lower at <1% 1
- In African American populations, prevalence is approximately 2.5% 1
- Han Chinese populations show higher prevalence rates of 10-15% 1
Clinical Significance of HLA-B51
- HLA-B51 is strongly associated with Behçet's disease, with a pooled odds ratio of 5.78 (95% CI 5.00-6.67) for developing the disease compared to non-carriers 3
- The association between HLA-B51 and Behçet's disease is consistent across different ethnic populations, supporting its role as a primary risk determinant 3
- The population-attributable risk for Behçet's disease related to HLA-B51 is estimated at 32-52% across various geographic areas 3
- In recent studies from the United Arab Emirates, 84% of Behçet's disease patients were HLA-B51 positive 4
Interesting Epidemiological Observations
- Some indigenous Amerindian populations have high HLA-B51 prevalence but no reported cases of Behçet's disease, suggesting that additional genetic or environmental factors are necessary for disease development 2
- HLA-B51 shows epistatic interaction with endoplasmic reticulum aminopeptidase (ERAP1), which may explain some of the variability in disease association across populations 5
- In moyamoya disease, HLA-B51 has been identified as one of several HLA antigens associated with the condition, particularly in patients over 10 years of age 1
Testing and Clinical Applications
- HLA-B51 testing is not routinely recommended as a screening test for the general population 6
- In patients with suspected Behçet's disease, HLA-B51 testing may provide supportive diagnostic information, though it is not included in the primary diagnostic criteria 7
- The strength of association between HLA-B51 and Behçet's disease varies according to sex, suggesting an interaction between this allele and disease characteristics 3
Understanding the prevalence of HLA-B51 in different populations is important for interpreting test results and assessing disease risk, particularly for conditions like Behçet's disease where this genetic marker plays a significant role in pathogenesis.