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COVER STORYThe urgent needfor new spermbiomarkersConventional semen analysis remains the gold standardfor the initial investigation of male infertility. However,semen analysis is today considered of only limited valuein predicting a couple’s chance of pregnancy with ART.Certainly, the uptake and success of ICSI have reduced thesignificance and perceived need for sperm quality tests; ICSIrequires only one sperm - even if morphologically abnormal andimmotile - for the procedure to be around 25% successful inmost European clinics. ICSI is now our most widely used meansof fertilisation in ART, but can we be satisfied with this modestlevel of success? Will a better test than semen analysis improveour results?Sperm DNA quality as a diagnostic testAs a diagnostic tool, sperm DNA damage has been shown to bemore reproducible than conventional semen parameters andmore predictive at numerous fertility check-points. 1 Forexample, men with sperm DNA fragmentation above adiagnostic threshold of 25% using the Comet assay or 30%using the Sperm Chromatin Structure assay (SCSA) have a highrisk of infertility. 2,3 So sperm DNA damage appears to exhibitbetter credentials as a novel biomarker for male infertility than asemen analysis.Semen analysis is of limitedvalue but remains the goldstandard of initial testing formale fertility. Will betterassays improve the outcomeof ICSI and IVF, asksandrologist Sheena Lewis.Sperm DNA quality as a prognostic test for ART outcomeSperm DNA damage is associated with longer times topregnancy than in fertile couples, with impaired embryocleavage and reduced implantation after IVF, and most closelywith increased risk of pregnancy loss after both IVF and ICSI.However, the lasting implications of sperm DNA damage maybe of even greater significance. As sperm have few repairmechanisms and oocytes can only repair a limited amount ofsperm DNA damage, such damage may remain in the germ linefor generations. Nature does not prevent a sperm with oxidativeDNA damage from reaching the oocyte, achieving fertilisationand thus contributing to mutations during embryonicdevelopment or even causing loss of the fetus. Damaged spermDNA may be incorporated into the embryonic genome, thusleading to errors in DNA replication, transcription andtranslation during embryogenesis, and t<strong>here</strong>by contributing to arange of human diseases in subsequent future generations. 4 Inparticular, sperm DNA may have an impact on both the shortand long-term health of children born by ART, with someFocus on Reproduction January 2012 27

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