Sperm mitochondrial DNA copy numbers in normal and abnormal semen
analysis: a systematic review and meta-analysis.
Abstract
Background: Normal mature sperm have a considerably reduced number of
mitochondria which provide the energy required for progressive sperm
motility. Literature suggests that disorders of sperm motility may be
linked to abnormal sperm mitochondrial number and function. Objectives:
To summarise the evidence from literature regarding the association of
mitochondrial DNA copy numbers and semen quality with a particular
emphasis on the spermatozoa motility. Search strategy: Standard
methodology recommended by Cochrane. Selection criteria: All published
primary research reporting on differences in mitochondrial DNA copy
numbers between the sperm of males with a normal and abnormal semen
analysis. Data collection and analysis: Using standard methodology
recommended by Cochrane we pooled results using a random effects model
and the findings were reported as a standardised mean difference. Main
results: We included 10 trials. The primary outcome was sperm
mitochondrial DNA copy numbers. A meta-analysis including five studies
showed significantly higher mitochondrial DNA copy numbers in abnormal
semen analysis as compared to normal semen analysis(SMD 1.08, 95% CI
0.74-1.43). Three other studies not included in the meta-analysis showed
a significant negative correlation between mitochondrial DNA copy
numbers and semen parameters. The quality of evidence was assessed as
good to very good in 60% of studies. Conclusions: Our review
demonstrates significantly higher mitochondrial DNA in human sperm cells
of men with abnormal semen analysis in comparison to men with normal
semen analysis. PROSPERO registration: CRD42019118841 Funding None
received