Frequency of HLA-C alleles in differentiated thyroid carcinoma in southeastern Spain.

BACKGROUND The development of thyroid carcinoma may be influenced genetically and has been associated with certain HLA alleles. HLA-C alleles have not been studied in depth, because available serology techniques have not been very reliable in detecting them. However, the development of molecular biology provided an efficient and reliable technique for allele detection. The aims of the current study were to determine whether there is a significant association between any HLA-C allele and differentiated thyroid carcinoma and to establish the possible susceptibility or protection alleles related to these tumors. METHODS HLA-C genotyping was performed in 63 patients undergoing surgery for differentiated thyroid carcinoma (57 patients with the papillary subtype and 6 patients with the follicular subtype). A representative sample of 100 nonrelated healthy Caucasians was used as a control group from the same geographic area. The polymerase chain reaction-sequence-specific primer technique was used for HLA-C genotyping. The clinical variables analyzed were age, gender, family history of thyroid pathology, residence in areas of endemic goiter, asymptomatic status, presence of hyperthyroidism, compressive symptoms, presence of an intrathoracic thyroid component, histologic variables of the tumor, and evolution. The chi-square test, the Mantel-Haenszel test, and the Bonferroni correction were used for the statistical analysis. RESULTS In the control group, a significant correlation was observed between the lower frequency of the HLA-Cw7 allele and the development of differentiated thyroid carcinoma (P < 0.05). Analysis of the different clinical variables revealed a relation between HLA-C alleles and three clinical situations: cervical lymph node involvement with HLA-Cw7 and HLA-Cw2, vascular involvement with HLA-Cw7 and HLA-Cw1, and cervical carcinoma recurrence with HLA-Cw1. However, after application of the Bonferroni correction, only the association between HLA-Cw7 and lymphatic (P(c) = 0.0483) or vascular involvement (P(c) = 0.0324) persisted. CONCLUSIONS The results revealed a relation between HLA-Cw7 and differentiated thyroid carcinoma. In future investigations, HLA-C typing may help to identify patients with a poor prognosis.