Introduction: The presence of components of the renin angiotensin system and tumour necrosis factor in a male reproductive tract supports the hypothesis that these substances may influence reproductive functions. It was proved that angiotensin II as a product of ACE has influence on sperm capacitation and motility. TNF-beta is released from T-lymphocytes and has the regulatory effect on steroidogenesis and spermatogenesis. Aberrations of these agents can result in infertility.
Objective: The aim of this study was to determine the allele frequency of ACE and TNF-beta genes in men with pathological sperm count and men with normal fertility. We examined the insertion/deletion (I/D) ACE and B1/B2 TNF-beta gene polymorphic alleles and analyzed their frequency in patients and fertile men.
Design: A pilot study.
Setting: 1st Clinic of Gynaecology and Obstetrics and Institute of Pathologic Physiology, Masaryk University, Brno, CR.
Material and methods: The genomic DNA was isolated from peripheral blood leukocytes by a standard method according to Sambrook in a group of 46 patients (33.4 +/- 7.2 years) with pathological sperm count (9 azoospermia, 21 severe oligoasthenospermia, 16 moderate oligoasthenospermia) and in a control group of 88 healthy men (31.2 +/- 9.3 years) with normal fertility. Polymerase chain reaction (PCR) was used for genom analysis. The method according to Rigat was used for the I/D ACE polymorphism. B1/B2 TNF-beta genotype of each patient was determined after Nco I digestion of the amplified product and subsequent agrose gel electrophoresis. Fisher's exact test and chi square test were used for statistical analysis.
Results: In the study we found these differences of allel frequency and their combination: 1. Combinations of the genotype II (ACE) + B1B2 (TNF-beta) and genotype II (ACE) + B2B2 (TNF-beta) were less frequent in patients (8.7%) than in fertile men (28.4%), this difference was statistically significant (p = 0.021). 2. Allele B1 (TNF-beta) was more frequent among patients (40.2%) than in the control group (29.5%), this difference was near to the point of statistical significance (p = 0.05). 3. Allele D (ACE) frequency was higher in men with pathological sperm count (52.2%) than in fertile men (44.9%), this difference was not statistically significant (p = 0.15).
Conclusion: The study has found different allele frequency of I/D ACE and B1/B2 TNF-beta genes polymorphism in men with pathological sperm count compared to men with normal fertility. These results could contribute to elucidate the genetic background of a male infertility.