The genetic integrity of the spermatozoan is essential for normal embryo development. A high level of DNA fragmentation in sperm cells may represent a cause of male infertility that conventional examinations - sperm concentration, motility analysis, morphology assessment - cannot detect.
- High sperm DNA fragmentation does not appear to affect fertilisation or the first or second embryo cleavage stages
- High sperm DNA fragmentation can affect embryo cleavage once the paternal genome is switched on, and subsequent blastocyst development
- Men with poor semen parameters are more likely to have high DNA fragmentation
- High sperm DNA fragmentation is also found in men with normal semen parameters
High Rates of Sperm DNA Fragmentation and Pregnancy
Embryos derived from sperm whose DNA is highly fragmented have a poor prognosis. Evidence suggests that this could result in initiation of apoptosis and mutations resulting in blastocyst arrest, miscarriage, abnormalities in the offspring and an increased susceptibility to childhood cancer. Protection against high DNA fragmentation may be afforded by younger oocytes which are much more efficient at DNA repair of defective sperm than older oocytes.
Causes of Sperm DNA Fragmentation
- Oxidative Stress
- Abnormalities in the regulation apoptosis
- Defective topoisomerase
- Infection
- Leucocytospermia
- Sperm cytoplasmic droplets
- Febrile illness
- Elevated testicular temperature
- Diet
- Drug use
- Cigarette smoking
- Exposure to environmental and occupational pollutants
- Advanced age
- Varicocoele
Indications for male patients who may benefit from the Test
- Unexplained infertility
- Arrested embryo development
- Poor blastocyst development
- Multiple failed IVF/ICSI treatment
- Recurrent miscarriage in partner
- Advanced age
- Varicocoele
- Poor semen parameters
- Exposure to harmful substances
Initial reports suggest that DNA damage occurs at the post-testicular level, so that testicular sperm may have a healthier DNA integrity than ejaculated sperm. Furthermore, studies show that ICSI may be a more effective treatment than IVF for sperm with a high DNA fragmentation.
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
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.
High DNA stainability (HDS): % sperm with immature chromatin and abnormal proteins. Levels in the > 25% range are considered negative for pregnancy outcome
