The POLG Gene Polymorphism in Iranian Varicocele-Associated Infertility Patients

Document Type: Original Article


1 Department of Biology, Science School, Yazd University, Yazd, Iran

2 Department of Anatomy, Research Clinical Center for Infertility, Shahid Sadughi University of Medical Sciences, Yazd, Iran


Varicocele is associated with impaired testicular function and male infertility, but the molecular mechanisms by which fertility is affected have not been satisfactorily explained. The aim of our study was to investigate whether or not the polymerase gamma (POLG) polymorphism is associated with Iranian varicocele patients.   
Materials and Methods
We determined the POLG CAG repeat length in DNA samples extracted from 40 varicocele patients and 30 control subjects by PCR-denature polyacrylamide gel electrophoresis and sequencing.
The distribution of the CAG repeat length in varicocele patients showed no notable difference from that in control subjects, but we found a significant statistical inverse correlation between 10/10 and 10/#10 genotypes and varicocele grade.
These findings indicate that POLG CAG repeats may affects the varicocele grade, but the mechanisms remain to be elucidated. 


1. Zini A, Blumenfeld A, Libman J, Willis J. Beneficial effect of microsurgical varicocelectomy on human sperm DNA integrity. Hum Reprod 2005; 20:1018-1021.

2. Moro E, Marin P, Rossi A, Garolla A, Ferlin A. Y chromosome microdeletions in infertile men with varicocele. Mol Cell Endocrinol 2000; 161:67-71.

3. Jarow JP, Coburn M, Sigman M. Incidence of varicoceles in men with primary and secondary infertility. Urology 1996; 47:73-76.

4. Mieusset R, Bujan L. Testicular heating and its possible contributions to male infertility: a review. Int J Androl  1995; 18:169-184.

5. Allamaneni SS, Naughton CK, Sharma RK, Thomas AJ, Jr., Agarwal A. Increased seminal reactive oxygen species levels in patients with varicoceles correlate with varicocele grade but not with testis size. Fertil Steril  2004; 82:1684-1686.

6. Kumar R, Venkatesh S, Kumar M, Tanwar M, Shasmsi MB, Gupta NP, et al. Oxidative stress and sperm mitochondrial DNA mutation in idiopathic oligoasthenozoospermic men. Indian J Biochem Biophys 2009; 46:172-177.

7. Talebi AR, Moein MR, Tabibnejad N, Ghasemzadeh J. Effect of varicocele on chromatin condensation and DNA integrity of ejaculated spermatozoa using cytochemical tests. Andrologia  2008; 40:245-251.

8. Bertazzoni U, Scovassi AI, Brun GM. Chick-embryo DNA polymerase gamma. Identity of gamma-polymerases purified from nuclei and mitochondria. Eur J Biochem. 1977; 81:237-248.

9. Zullo SJ, Butler L, Zahorchak RJ, Macville M, Wilkes C, Merril CR. Localization by fluorescence in situ hybridization (FISH) of human mitochondrial polymerase gamma (POLG) to human chromosome band 15q24-->q26, and of mouse mitochondrial polymerase gamma (Polg) to mouse chromosome band 7E, with confirmation by direct sequence analysis of bacterial artificial chromosomes (BACs). Cytogenet Cell Genet 1997; 78:281-284.

10. Trifunovic A, Wredenberg A, Falkenberg M, Spelbrink JN, Rovio AT, Bruder CE, et al. Premature ageing in mice expressing defective mitochondrial DNA polymerase. Nature  2004; 429:417-423.

11. Luoma PT, Eerola J, Ahola S, Hakonen AH, Hellstrom O, Kivisto KT, et al. Mitochondrial DNA polymerase gamma variants in idiopathic sporadic Parkinson disease. Neurology 2007; 69:1152-1159.

12. Heidari MM, Houshmand M, Hosseinkhani S, Nafissi S, Scheiber-Mojdehkar B, Khatami M. Association between trinucleotide CAG repeats of the DNA polymerase gene (POLG) with age of onset of Iranian Friedreich's ataxia patients. Neurol Sci 2008 ; 29:489-493.

13. Krausz C, Guarducci E, Becherini L, degl'Innocenti S, Gerace L, Balercia G, et al. The clinical significance of the POLG gene polymorphism in male infertility. J Clin Endocr Metab 2004 ; 89:4292-4297.

14. Rovio A, Tiranti V, Bednarz AL, Suomalainen A, Spelbrink JN, Lecrenier N, et al. Analysis of the trinucleotide CAG repeat from the human mitochondrial DNA polymerase gene in healthy and diseased individuals. Eur J Hum Genet 1999; 7:140-146.

15. Rovio AT, Marchington DR, Donat S, Schuppe HC, Abel J, Fritsche E, et al. Mutations at the mitochondrial DNA polymerase (POLG) locus associated with male infertility. Nat Genet 2001; 29:261-262.

16. World Health Organization, WHO Laboratory Manual for the Examination of Human Semen and Sperm–Cervical Mucus Interaction. 4th ed. New York: Cambridge University Press; 1999.

17. Ropp PA,Copeland WC.Cloning and characterization of the human mitochondrial DNA polymerase, DNA polymerase gamma. Genomics 1996; 36:449-458.

18. Van Goethem G, Dermaut B, Lofgren A, Martin JJ, Van Broeckhoven C. Mutation of POLG is associated with progressive external ophthalmoplegia characterized by mtDNA deletions. Nat Genet 2001; 28:211-212.

19. Report on varicocele and infertility. Fertil Steril 2008; 90:S247-249.

20. Richens J. Main presentations of sexually transmitted infections in men. Br Med J 2004 ; 328:1251-1253.

21. St John JC, Jokhi RP, Barratt CL.Men with oligoasthenoteratozoospermia harbour higher numbers of multiple mitochondrial DNA deletions in their spermatozoa, but individual deletions are not indicative of overall aetiology. Mol Hum Reprod 2001; 7:103-111.

22. Lamantea E, Tiranti V, Bordoni A, Toscano A, Bono F, Servidei S, et al. Mutations of mitochondrial DNA polymerase gammaA are a frequent cause of autosomal dominant or recessive progressive external ophthalmoplegia. Ann Neurol  2002; 52:211-219.

23. Del Bo R, Bordoni A, Sciacco M, Di Fonzo A, Galbiati S, Crimi M, et al. Remarkable infidelity of polymerase gammaA associated with mutations in POLG1 exonuclease domain. Neurology  2003; 61:903-908.

24. Selvi Rani D, Vanniarajan A, Gupta NJ, Chakravarty B, Singh L, Thangaraj K. A novel missense mutation C11994T in the mitochondrial ND4 gene as a cause of low sperm motility in the Indian subcontinent. Fertil Steril  2006; 86:1783-1785.

25. Aknin-Seifer IE, Touraine RL, Lejeune H, Jimenez C, Chouteau J, Siffroi JP, et al. Is the CAG repeat of mitochondrial DNA polymerase gamma (POLG) associated with male infertility? A multi-centre French study. Hum Reprod 2005; 20:736-740.