Spontaneous and bleomycin-induced chromosome damage in non cancer thyroid patients

P>Background Presence of chromosome damage in lymphocytes of patients affected by several diseases, including cancer, was detected by the micronucleus (MN) assay. Individual susceptibility to DNA damage, considered as a risk factor for cancer, can be also evaluated using the bleomycin (BLM) sensitivity test. Materials and methods We aimed to evaluate spontaneous or BLM-induced MN frequencies in autoimmune (AI, n = 19) and non autoimmune (NAI, n = 11) thyroid patients, not receiving 131I radiometabolic therapy with respect to a control group of 18 healthy subjects. According to thyroid function, patients were also divided into hypothyroid (n = 10), euthyroid (n = 13) or hyperthyroid (n = 7) subjects. Results Spontaneous MN frequencies of AI and NAI patients did not differ from those of controls. Hypothyroid patients had more elevated MN basal levels (9 center dot 00 +/- 1 center dot 71 parts per thousand) than hyperthyroid (3 center dot 75 +/- 1 center dot 17 parts per thousand, P < 0 center dot 05) and euthyroid (5 center dot 38 +/- 0 center dot 97 parts per thousand, P < 0 center dot 01) patients or healthy subjects (4 center dot 17 +/- 0 center dot 63 parts per thousand, P < 0 center dot 01). In particular, the hypothyroid AI group showed the highest value (9 center dot 79 +/- 2 center dot 26 parts per thousand, P < 0 center dot 01). All thyroid patients responded differently to BLM than controls (39 center dot 90 +/- 2 center dot 48 parts per thousand vs. 31 center dot 08 +/- 2 center dot 51 parts per thousand, P = 0 center dot 0377). The NAI group had BLM-induced MN levels (45 center dot 00 +/- 2 center dot 56 parts per thousand) significantly higher (P = 0 center dot 0215) than AI patients (36 center dot 95 +/- 3 center dot 49 parts per thousand) or healthy subjects (31 center dot 08 +/- 2 center dot 51 parts per thousand). No significant difference was seen when patients were stratified according to autoimmunity. Conclusions We report that hypothyroid patients exhibit a moderate increase in the level of spontaneous genome damage, and that AI thyroid patients resulted to be less sensitive than NAI patients to the mutagen sensitivity test. In prospective, it may be of interest to reinvestigate hypothyroid patients when correction of their dysfunction is achieved.