RESUMO
A limited number of studies have been performed so far on the polymorphism in the transmembrane region (exon 5) of the major histocompatibility complex class I chain-related gene A (MICA) in patients with melanoma. However, the influence of MICA polymorphism in extracellular domains (exons 2, 3, and 4) has not been investigated on melanoma disease. This study aims to characterize the influence of extracellular MICA polymorphism, and its previously described linkage disequilibrium with HLA-B locus, on patients with cutaneous melanoma from southeastern Spain. For this purpose, MICA and HLA-B genotyping was performed in 233 patients and 200 ethnically matched controls by luminex technology. Patients were classified according to the presence of methionine or valine at codon 129 of MICA gene. We found a high frequency of MICA(*)009 in melanoma patients compared with controls (P = 0.002, Pc = 0.03). Our results also showed an association between MICA(*)009 and HLA-B(*)51 alleles in both patients and controls. This association was stronger in patients than controls (P = 0.015). However, a multivariate logistic regression model showed that neither MICA(*)009 nor the combination MICA(*)009/HLA-B(*)51 was associated with melanoma susceptibility. No relationship was observed between MICA-129 dimorphism and melanoma nor when MICA polymorphism was evaluated according to clinical findings at diagnosis.
