The large sample size of Brazilian patients for the case control genetic tests and replication of these using analytical approach on a very different Vietnamese population, demonstrates that leprosy, caused by Mycobacterium leprae is associate with some HLA alleles. According to a paper titled “HLA-DRB1*04 and DRB1*10 are associated with resistance and susceptibility, respectively, in Brazilian and Vietnamese leprosy patients” (Genes and Immunity, 2007, 8, 320-324), Vanderborght et al. mention that 400000 people get leprosy worldwide per year. While the majority of people are resistant to leprosy, some are still susceptible to the bacteria.
While geography plays an important role in any disease, some genes seem to play an important part in leprosy. Vanderborght’s group studied Brazilian and Vietnamese patients and families respectively and found that HLA-DRB1*07 and HLA-DRB1*04 genes are resistant to leprosy while DRB1*15 and DRB1*10 are susceptible. The authors also found ethnicity specific effect of DRB1*15 in Afro-Brazilians and DRB1*07 in Euro-Brazilians.
While this paper is interesting from immunological perspective, it raises the question about genetic makeup and diseases. While one group may possess resistant allele(s) to a disease, others may carry susceptible gene(s) to that particular disease. A myriad of questions arise from such findings—what does this mean at the dawn of gene therapy? Will such information be used ethically in future? What is also interesting to me is can these polymorphisms in HLA be used to track Human migration (out of Africa)? Is there a correlation between human evolution/migration and diseases?