DNA double-strand break repair gene mutation and the risk of papillary thyroid microcarcinoma: a case–control study

Objective To study the relationship between DNA double-strand break (DSB) repair gene mutations and the risk of papillary thyroid microcarcinoma (PTMC). Methods One hundred patients with PTMC or benign thyroid nodules (BTNs) at Henan Cancer Hospital were retrospectively analyzed. The DSB repair capacity of peripheral blood T lymphocytes in the two groups was assessed by flow cytometry. Data were compared using Student’s t-test to evaluate the relationship between DSB repair capacity and the risk of PTMC. Factors influencing DSB repair capacity were analyzed by multivariate logistic regression analysis. The relationship between PTMC and DSB repair capacity was analyzed by univariate analysis. Targeted next-generation DNA sequencing was applied to screen and analyze DSB repair genes related to PTMC. Results The DSB repair capacity was 31.30% in the PTMC group and 44.40% in the BTN group, with that of the former being significantly lower ( P < 0.05). Multivariate logistic regression analysis of age, sex, obesity status, radiation and other factors showed that radiation exposure was positively correlated with reduced DSB repair capacity( OR = 3.642; 95% CI 1.484–8.935, P = 0.020). Moreover, univariate analysis showed that a reduction in DSB repair capacity was a risk factor for PTMC ( OR = 2.333; 95% CI 1.027–5.300, P = 0.043).Targeted next-generation DNA sequencing was performed on the DSB repair genes discovered, and those that were mutated in association with PTMC were Rad50 and FANCA; Rad51 mutations were related to BTN. Conclusion Radiation exposure is positively associated with induced DSB repair gene mutations, which may cause a reduced capacity for DSB repair and eventually lead to PTMC.