Further evidence of the role of HLA-DR4 in the genetic susceptibility to actinic prurigo.

BACKGROUND: Actinic prurigo (AP) is triggered by sun exposure. Its prevalence in Mexicans seems to be particularly high, which suggests a genetic susceptibility.

OBJECTIVE: Our purpose was to determine the role of major histocompatibility complex (MHC) genes in the genetic susceptibility to AP.

METHODS: Fifty-six Mexican Mestizo patients with AP underwent serologic typing for HLA class I and class II antigens. Class II MHC genes were also studied by DNA analysis. Findings in patients were compared with 100 ethnically matched healthy controls.

RESULTS: We found that 92.8% of patients with AP were HLA-DR4 positive (corrected p = 0.002; odds ratio [OR] = 10.1). The class I antigens HLA-A28 and HLA-B39 (B16) were also significantly increased (p < or = 0.000001, OR = 20.9 and p = 0.0001, OR = 6.7, respectively) compared with normal controls. Allele-specific oligonucleotide DR4 subtyping showed that 80.7% of HLA-DR4+ patients with AP were also positive for the DRB1*0407 allele.

CONCLUSION: These results confirm the role of HLA-DR4 (DRB1*0407) in the genetic susceptibility to AP and raise the possibility of a role for class I MHC antigens HLA-A28 and B16 in Mexican patients.