Leprosy is a chronic
infectious disease caused by Mycobacterium leprae, which mainly affects the skin and nervous system. The disease has several clinical forms. This study investigated the
MICA and
HLA-B genes in 223 samples from
leprosy patients and 201 samples from healthy individuals matched for age, gender and ethnical background. Of the patients, 153 had multibacillary, 45 paucibacillary and 25 indeterminate
leprosy. The aim of this case-control study was to assess whether the
MICA alleles influence susceptibility for
leprosy or affect the subtype of the disease in a population of southern Brazil. There were significant differences in frequencies of the
MICA*027 allele (4.7% vs 1.8%, P-value = 0.01, OR = 0.37; 95% CI = 0.16-0.85) between
leprosy patients and controls, and of the
MICA*010 (4.5% vs 1.6%, P-value = 0.05, OR = 0.35, 95% CI = 0.13-0.97) and
MICA*027 alleles (4.7% vs 1.3%, P-value = 0.01; OR = 0.27; 95% CI = 0.09-0.79) between
multibacillary leprosy patients and the control group. There were no significant differences in the frequency of
MICA alleles between
paucibacillary leprosy patients and controls. Thus, the
MICA*027 allele is associated with a protective effect for
leprosy per se, while the
MICA*010 and
MICA*027 alleles are associated with protection against
multibacillary leprosy, the most severe clinical subtype.