Sister chromatid exchanges, chromosome aberrations and micronuclei in female lymphocytes: correlations with biological rhythms, miscarriages and contraceptive pill use

Our study looked at the variation in peripheral blood lymphocytes, during t he menstrual cycle, of frequencies of sister chromatid exchanges (SCE) and micronuclei (MN) in 819 women and cells with aberrant chromosomes (CA) in a selected sample of 136 volunteers. We observed significant fluctuations in SCE and CA frequencies: SCEs reached a maximum value at the end of menstru ation and a low at the time of ovulation, whereas CAs showed a continuous i ncrease from the beginning of the menstrual cycle up to the time of ovulati on and a progressive decrease thereafter. MN frequency did not fluctuate in a statistically significant way. No statistically significant differences in SCE, CA and MN frequencies were observed when fertile women were compare d with women taking the contraceptive pill or those in menopause and no dif ference was found between women who had undergone physiological or surgical ly induced menopause. Moreover, no difference was found between women with a history of miscarriages and matched controls. These data together suggest that the natural variations in sexual hormone levels, but not those due to the contraceptive pill or their reduction at menopause, can contribute in modulating the baseline frequencies of SCEs and CAs, Moreover, these data s uggest that the increased risks either of producing a chromosome imbalance in the progeny (eliciting miscarriages) or of occurrence of gynaecological diseases is not predictable by evaluating cytogenetic end-points in periphe ral blood lymphocytes.