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Almost 50% of all cases of infertility may be associated with a male factor. A semen analysis that measures sperm concentration, motility and morphology has classically been used as the gold standard test for determining a man’s fertility. However, this test does not provide any information about the genetic constitution of the sperm, which is essential for normal embryo development. Thus a high level of DNA damage in sperm cells may represent a cause of male infertility that conventional examinations cannot detect.
Sperm DNA fragmentation is significantly higher in infertile men and while men with poor semen parameters are more likely to have high sperm DNA fragmentation, high sperm DNA fragmentation is also found in men with normal semen parameters1 who may be diagnosed with unexplained infertility.
Embryos derived from sperm whose DNA is highly fragmented have a poor prognosis2,3. High sperm DNA fragmentation is more likely to affect embryos from day two of development once the paternal genome is switched on and it impairs subsequent blastocyst development2,3. There is some evidence to suggest that DNA damage in the embryo could result in cell degeneration and gene mutations, leading to arrested embryo development, miscarriage, abnormalities in the offspring and an increased susceptibility to childhood cancers3,4.
In couples where the male partner has a high percentage of sperm with fragmented DNA, many studies indicate that the chances of a successful pregnancy are significantly reduced5-13. One systematic review article suggests that current sperm DNA fragmentation tests have limited capacity to predict the chance of pregnancy following assisted conception treatment14, however several large studies, systematic reviews and meta-analyses have revealed that high sperm DNA fragmentation is associated with reduced natural pregnancy rates6 and assisted conception pregnancy rates5,6,10,13 as well as live birth rates11. In addition, sperm with high DNA fragmentation lead to higher miscarriage rates from spontaneous conceptionions7,8 as well as following assisted conception treatment6,9,10,12. Overall the results of these studies lend support for the value of testing for sperm DNA fragmentation to identify possible causes for unexplained infertility, failed IVF treatment cycles or recurrent miscarriage15,16.
A major causative factor for sperm DNA damage is oxidative stress due to excessive production of reactive oxygen species4,17-19. Other factors include defects in sperm chromatin packaging and DNA repair mechanisms as well as abnormalities in the regulation of programmed cell death (abortive apoptosis) which is vital for regulating sperm production17- 19. Increased sperm DNA fragmentation is also associated with a variety of exogenous factors listed in the table below4,18,20.
The test we offer is the sperm chromatin structure assay (SCSA®)16,21,22. This test is an effective method for measuring DNA damage in thousands of sperm in an ejaculate. It measures the susceptibility of sperm DNA to denaturation when it is exposed to heat or acids. Sperm are stained with a fluorescent probe that interacts with the DNA molecule. The fluorescence signal changes when the DNA is fragmented, and this is monitored using a flow cytometer. The SCSA® test has been developed using human and animal models over the last 35 years and is one of the most statistically robust tests available for sperm DNA fragmentation. It is a standardised, validated CLIA approved test with high reproducibility and low variability16,21,22.
The test reports two indicators of DNA damage:
1. DNA Fragmentation Index (%DFI: % sperm cells containing damaged DNA)
Results are reported showing 4 statistical categories of fertility potential:
≤ 15% DFI = excellent to good sperm DNA integrity
> 15 to < 25% DFI = good to fair sperm DNA integrity
> 25 to < 50% DFI = fair to poor sperm DNA integrity
≥ 50% DFI = very poor sperm DNA integrity
Note: The above values relate to natural and IUI conceptions. The statistically significant DFI threshold for subfertility has been established at > 25 %.
Normal full-term pregnancies are possible with an elevated DFI, but the higher the level of fragmentation, the greater the incidence of reduced term pregnancies and miscarriage. The above values relate to natural and IUI conceptions. When % DFI is above 25%, current literature suggests that the patient either try to reduce the DFI by medical intervention or change of lifestyle, or skipping IUI and go on to IVF ICSI for greatest success (www.scsatest.com for details).
Hypothesis: A high ratio of moderate DFI to high DFI sperm may be the most negative since moderate DFI sperm have normal nuclear morphology and will likely fertilise but may have DNA damage beyond the repair capacity of eggs.
2. High DNA stainability (HDS): % sperm with immature chromatin and abnormal ratios of histones to protamines. Levels in the > 25% range are considered negative for pregnancy outcome
Some causes of DNA fragmentation cannot be treated, but if the damage is caused by oxidative stress, then a change in lifestyle and a diet designed to protect against oxidative stress may help reduce the levels of DNA fragmentation in some of these cases16-18,23,24. Although initial studies using antioxidant supplementation to reduce DNA damage are promising16,25, care must be taken in overprescribing and more evidence is required24. Treatment of infection with antibiotics may also be beneficial in reducing sperm DNA damage26, but again it is essential that there is clear identification of bacteria before antibiotics are prescribed. Varicocoele is the leading known cause of male infertility and it is associated with sperm DNA damage27-29. There is now growing evidence to show that varicocoele repair may improve sperm DNA integrity28-32. Initiatives to reduce the levels of fragmentation can be assessed by undertaking a second test three months after the first.
Initial reports suggest that DNA damage occurs at the post-testicular level, so that testicular sperm may have a healthier DNA integrity than ejaculated sperm33,34. Furthermore, several studies show that ICSI may be a more effective treatment than IVF for sperm with high DNA fragmentation since its impact on fertilisation and pregnancy rates are not as detrimental compared to IVF6,10,11. This view is borne out by a large Swedish study based on 1633 IVF or ICSI cycles which reported a significant decrease in fertilisation rate, embryo quality and live birth rate following IVF using sperm with high DNA damage, whereas outcomes with ICSI treatment were not significantly affected by the quality of the sperm DNA12.
The test provides a reliable analysis of sperm DNA integrity that may help to identify men who are at risk of failing to initiate a healthy ongoing pregnancy. Information about sperm DNA integrity may help in the clinical diagnosis, management and treatment of male infertility and may be of prognostic value in assessing outcome of assisted conception treatment15,16. Identification of high levels of DNA fragmentation in the sperm may guide the clinician as to whether sperm donation may be appropriate. Sperm DNA fragmentation testing may help couples make an informed choice regarding their subsequent course of treatment.
Additional information downloads:
Sperm DNA Fragmentation and Aneuploidy/Sample Information Sheet and Request Form (Word doc, 56Kb)
1. Evgeni E, Charalabopoulos K, Asimakopoulos B (2014) Human sperm DNA fragmentation and its correlation with conventional semen parameters J Reprod Infertil 15(1):2-14
2. Simon L, Murphy K, Shamsi MB, Liu L, Emery B, Aston KI, Hotaling J, Carrell DT. (2014) Paternal influence of sperm DNA integrity on early embryonic development. Hum Reprod 29(11):2402-12
3. Lewis SE, John Aitken R, Conner SJ, Iuliis GD, Evenson DP, Henkel R, Giwercman A, Gharagozloo P (2013) The impact of sperm DNA damage in assisted conception and beyond: recent advances in diagnosis and treatment. Reprod Biomed Online 27(4):325-37.
4. Gavriliouk D, Aitken R.(2015) Damage to Sperm DNA Mediated by Reactive Oxygen Species: Its Impact on Human Reproduction and the Health Trajectory of Offspring. Adv Exp Med Biol 868:23-47
5. Speyer BE, Pizzey AR, Ranieri M, Joshi R, Delhanty JD and Serhal P (2010) Fall in implantation rates following ICSI with sperm with high DNA fragmentation. Hum Reprod. 25 (7):1609-18.
6. Zini A (2011) Are sperm chromatin and DNA defects relevant in the clinic? Syst Biol Reprod Med 57(1-2):78-85
7. Brahem S, Mehdi M, Landolsi H, Mougou S, Elghezal H and Saad A. (2011) Semen parameters and sperm DNA fragmentation as causes of recurrent pregnancy loss. Urology. 2011 Oct;78(4):792-6
8. Kumar K, Deka D, Singh A, Mitra DK, Vanitha BR, Dada R. (2012) Predictive value of DNA integrity analysis in idiopathic recurrent pregnancy loss following spontaneous conception. J Assist Reprod Genet. 29 (9):861-7.
9. Robinson L, Gallos ID, Conner SJ, Rjkhowa M, Miller D, Lewis S, Kirkman-Brown J and Coomarasamy A (2012) The effect of sperm DNA fragmentation on miscarriage rates: a systematic review and meta-analysis Hum. Reprod. 27 (10): 2908-2917
10. Zhao J, Zhang Q, Wang Y, Li Y (2014) Whether sperm deoxyribonucleic acid fragmentation has an effect on pregnancy and miscarriage after in vitro fertilization/intracytoplasmic sperm injection: a systematic review and meta-analysis. Fertil Steril 102(4):998-1005
11. Osman A, Alsomait H, Seshadri S, El-Toukhy T, Khalaf Y (2015) The effect of sperm DNA fragmentation on live birth rate after IVF or ICSI: a systematic review and meta-analysis.. Reprod Biomed Online 30 (2):120-7
12. Oleszczuk K, Giwercman A and Bungum M (2016) Sperm chromatin structure assay in prediction of in vitro fertilization outcome Andrology, 2016, 4, 290–296
13. Simon L, Zini A, Dyachenko A, Ciampi A, Carrell DT (2017) A systematic review and meta-analysis to determine the effect of sperm DNA damage on in vitro fertilization and intracytoplasmic sperm injection outcome Asian Journal of Andrology 19, 80–90
14. Cissen M, Wely MV, Scholten I, Mansell S, Bruin JP, Mol BW, Braat D, Repping S, Hamer G (2016) Measuring Sperm DNA Fragmentation and Clinical Outcomes of Medically Assisted Reproduction: A Systematic Review and Meta-Analysis. PloS One 11(11):e0165125. doi: 10.1371/journal.pone.0165125.
15. Agarwal A, Majzoub A, Esteves SC, Ko E, Ramasamy R, Zini A. (2016) Clinical utility of sperm DNA fragmentation testing: practice recommendations based on clinical scenarios. Transl Androl Urol. 5(6):935-950.
16. Evenson D, Gharagozloo P, Aitken RJ (2017) Sperm Chromatin Structure Assay (SCSA®): The Clinical Utility of Measuring Sperm DNA Damage and its Potential Improvement with Supplemental Antioxidants. JSM Invitro Fertil 2(1): 1008
17. Aitken RJ, Smith TB, Jobling MS, Baker MA, De Iuliis GN (2014) Oxidative stress and male reproductive health. Asian J Andrology 16: 31–38
18. Wright C, Milne S, Leeson H (2014) Sperm DNA damage caused by oxidative stress: modifiable clinical, lifestyle and nutritional factors in male infertility. Reprod Biomed Online 28:684-703
19. Gunes S, Al-Sadaan M, Agarwal A (2015) Spermatogenesis, DNA damage and DNA repair mechanisms in male infertility. RBMOnline 31(3):309-19
20. Humm KC and Sakkas D (2013) Role of increased male age in IVF and egg donation: is sperm DNA fragmentation responsible? Fertil Steril 99 (1):30-6.
21. Evenson DP (2013) Sperm chromatin structure assay (SCSA®). Methods Mol Biol. 927:147-64.
22. Evenson DP (2016) The Sperm Chromatin Structure Assay (SCSA(®)) and other sperm DNA fragmentation tests for evaluation of sperm nuclear DNA integrity as related to fertility. Animal Reprod Sci 169:56-75.
23. Gharagozloo P, Aitken RJ (2011) The role of sperm oxidative stress in male infertility and the significance of oral antioxidant therapy. Hum Reprod. 26 (7):1628-40
24. Menezo Y, Evenson D, Cohen M, Dale B. (2014) Effect of antioxidants on sperm genetic damage. Adv Exp Med Biol 791:173-89
25. Showell MG, Mackenzie-Proctor R, Brown J, Yazdani A, Stankiewicz MT, Hart RJ (2014) Antioxidants for male subfertility. Cochrane Database Syst Rev 12, CD007411–CD007411.
26. Moskovtsev SI, Lecker I, Mullen JB, Jarvi K, Willis J, White J, Lo KC (2009) Cause-specific treatment in patients with high sperm DNA damage resulted in significant DNA improvement. Syst Biol Reprod Med. 55(2):109-15
27. Zini A and Dohle G (2011) Are varicoceles associated with increased deoxyribonucleic acid fragmentation? Fertil Steril. 96 (6):1283-7
28. Wang YJ, Zhang RQ, Lin YJ, Zhang RG, Zhang WL. (2012) Relationship between varicocele and sperm DNA damage and the effect of varicocele repair: a meta-analysis. Reprod Biomed Online. 25 (3):307-14
29. Smit M, Romijn JC, Wildhagen MF, Veldhoven JL, Weber RF, Dohle GR. (2013) Decreased sperm DNA fragmentation after surgical varicocelectomy is associated with increased pregnancy rate. J Urol. 189 (1 Suppl):S146-50.
30. Ni K, Spiess AN, Schuppe HC, Steger K (2016) The impact of sperm protamine deficiency and sperm DNA damage on human male fertility: a systematic review and meta-analysis. Andrology 4(5):789-99.
31. Althalil N, San Gabriel M, Zini A (2016) Beneficial effects of microsurgical varicocoelectomy on sperm maturation, DNA fragmentation, and nuclear sulfhydryl groups: a prospective trial. Andrology 4(6):1204-1208.
32. Cho CL, Esteves SC, Agarwal A (2016) Novel insights into the pathophysiology of varicocele and its association with reactive oxygen species and sperm DNA fragmentation. Asian J Androl 18(2):186-93.
33. Mehta A, Bolyakov A, Schlegel PN, Paduch DA (2015) Higher pregnancy rates using testicular sperm in men with severe oligospermia. Fertil Steril 104(6):1382-7.
34. Esteves SC, Sanchez-Martin F, Sanchez-Martin P, Schneider DT, Gosalvez J (2015) Comparison of reproductive outcome in oligozoospermic men with high sperm DNA fragmentation undergoing intracytoplasmic sperm injection with ejaculated and testicular sperm. Fertil Steril 104(6):1398-1405