Clinical implications of sperm DNA damage

Traditionally, the diagnosis of male infertility has relied upon microscopic assessment and biochemical assays to determine human semen quality. These tests are essential to provide the fundamental information on which clinicians base their initial diagnosis. However, none of these parameters addresses sperm function and their clinical value in predicting fertility is questionable. The advent of intracytoplasmic sperm injection (ICSI) has further reduced the significance and perceived need for sperm quality tests since ICSI requires only one sperm for the procedure to be successful. Even the conventional measures of sperm quality in terms of normal morphology or motility are not necessary for successful ICSI. Funding of andrological research has been neglected and improvement in assisted reproductive technology (ART) success has suffered as a consequence. Testing of sperm DNA damage shows much promise both as a diagnostic test for male infertility and a prognostic test for ART outcomes. It has been shown to be closely associated with numerous fertility outcomes including negative relationships with fertilization, embryo quality, implantation and positive relationships with miscarriage and childhood diseases. Here we report the relationships between in vitro fertilisation, ICSI pregnancy rates and sperm DNA damage, using the Comet assay to measure DNA fragmentation and also a novel test to measure modified bases, as a indication of oxidative DNA injury.