DNA fragmentation in brighter sperm predicts male fertility independently from age and semen parameters

Detecting sperm DNA fragmentation by means of TUNEL/PI predicts male fertility status independently from age and semen parameters, providing additional information in routine semen analysis.

Monica Muratori, Ph.D., Sara Marchiani, Ph.D., Lara Tamburrino, Ph.D., Marta Cambi, Ph.D., Francesco Lotti, M.D., Ilaria Natali, Ph.D., Erminio Filimberti, Ph.D., Ivo Noci, M.D., Gianni Forti, M.D., Mario Maggi, M.D., Elisabetta Baldi, Ph.D.

Volume 104, Issue 3, Pages 582-590


To evaluate whether sperm DNA fragmentation (sDF), measured in brighter, dimmer, and total populations, predicts natural conception, and to evaluate the intra-individual variability of sDF.

Prospective study.

Outpatient clinic and diagnostic laboratory.

A total of 348 unselected patients and 86 proven fertile men.


Main Outcome Measure(s):
sDF was revealed with the use of terminal deoxynucleotide transferase–mediated dUTP nick-end labeling (TUNEL)/propidium iodide (PI). Receiver operating characteristic (ROC) curves were built before and after matching fertile men to patients for age (76:152) or semen parameters (68:136) or both (49:98). Intra-individual variability of sDF was assessed over 2 years.

Brighter (area under ROC curve [AUC] 0.718 ± 0.54), dimmer (AUC 0.655 ± 0.63), and total (AUC 0.757 ± 0.54) sDF predict male fertility in unmatched and age- or semen parameters–matched subjects. After matching for both age and semen parameters, only brighter (AUC 0.711 ± 0.83) and total (AUC 0.675 ± 0.92) sDF predict male fertility. At high values of total sDF, brighter predicts natural conception better than total sDF. Intra-individual coefficients of variation of sDF were 9.2 ± 8.6% (n = 25), 12.9 ± 12.7% (n = 53), and 14.0 ± 12.6% (n = 70) over, respectively, 100-day and 1- and 2-year periods, appearing to be the most stable of the evaluated semen parameters.

The predictive power of total sDF partially depends on age and semen parameters, whereas brighter sDF independently predicts natural conception. Therefore, brighter sDF is a fraction of sDF that adds new information to the routine semen analysis. At high levels of sDF, distinguishing the two sperm populations improves the predictive power of sDF. Overall, our results support the idea that TUNEL/PI can be of clinical usefulness in the male fertility workup.

  • Jason M. Franasiak

    A very interesting manuscript. The male analysis is often fraught with large changes in values over time making it challenging to make a distinction between changes in biology over time vs. changes in reproducibility of the test. I found the CV data over 100-day period to be helpful. Do the authors have a theory as to why this CV increases when analyzed over a longer period of time? Many thanks.

    • Monica Muratori

      Many thanks for appreciating our work. Regarding your question, I think that the longer the time between the two tests, the higher the probability that an unknown condition able to affect sDF occurs in that time. It is also possible that those subjects experiencing an increase of CV over time, forgot to report some factors known to change sDF levels, in the questionnaire.

      • Jason M. Franasiak

        Many thanks for your reply

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