Mitochondrial haplotype does not influence sperm motility in a UK population of men.
BACKGROUND
Sperm motility is regulated by mitochondrial enzymes that are partially encoded by mitochondrial DNA (mtDNA). MtDNA has therefore been suggested as a putative genetic marker of male fertility. However, recent studies in different populations have identified both significant and non-significant associations between mtDNA variation and sperm motility. Here, we tested whether mtDNA variation was associated with sperm motility in a large cohort of men from the UK, to test the robustness of previous studies and the reliability of mtDNA as a marker of poor sperm motility.


METHODS
A total of 463 men attending for semen analysis as part of infertility investigations were recruited from a UK laboratory. Sperm motility was measured using both computer-assisted sperm analysis and traditional manual measurements. MtDNA haplogroup and haplotype were determined in 357 and 298 men, respectively, using single nucleotide polymorphism (SNP) markers throughout the mtDNA genome, and compared with sperm motility data. The linkage between the SNP markers, and possible associations between individual SNPs and motility, were also investigated.


RESULTS
We found no statistical association between haplogroup or haplotype and sperm motility, regardless of how it was measured (P > 0.05 in all cases). Moreover, individual SNPs which were in linkage disequilibrium and dispersed across the mitochondrial genome, and therefore sensitive to mtDNA variation, were not predictive of sperm motility.


CONCLUSIONS
Mitochondrial haplotype is unlikely to be a reliable genetic marker of male factor infertility.
Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK. jim_mossman@brown.edu
Jim A
JA
Mossman
Jon
J
Slate
Tim R
TR
Birkhead
Harry D
HD
Moore
Allan A
AA
Pacey
D000328:Adult; D015331:Cohort Studies; D004272:DNA, Mitochondrial / Q000737:chemistry*; D005819:Genetic Markers; D014644:Genetic Variation; D006239:Haplotypes; D006801:Humans; D015810:Linkage Disequilibrium; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D025341:Principal Component Analysis; D013081:Sperm Motility / Q000235:genetics*; D006113:United Kingdom
D004272:DNA, Mitochondrial; D005819:Genetic Markers