The association of aromatase （CYP19） gene variants wil sperm concentration and motility

The irreversible transformation of androgens into oestrogens is catalysed by cytochrome P450 aromatase. In the present study, we explored the contribution of the （TTTA）n polymorphism in the aromatase gene （CYP19） to sperm concentration and motility. Ninety normozoospermic and 60 oligospermic men were examined during infertility examinations. DNA was extracted from spermatozoa, and the CYP19（TTTA）n polymorphism was genotyped by PCR. Genotype analysis revealed six CYP19（TTTA）n alleles with 7-12 repeats. The allelic distribution of the CYP19（TTTA）n polymorphism differed between normozoospermic and oligospermic men （P〈0.01）. Oligospermic men less frequently had long CYP19 alleles than did normozoospermic men （25 and 37.8%, respectively; P〈0.02）. The higher frequency of short CYP19alleles in oligospermic men compared to normozoospermic men （43.3 and 28.3%, respectively; P〈0.01） was primarily due to the distribution of the CYP19 （TTTA）7 allele. The CYP19 （TTTA）7 allele was associated with lower sperm concentration in normozoospermic men {P〈0.01） and in the total study population {P〈0.01）; it was also associated with lower sperm motility in normozoospermic men （P〈0.05） and in the total study population （P〈0.01）. In conclusion, the CYP19 （TTTA）7 allele probably impairs aromatase activity, which in turn alters aromatase and oestrogen levels in the testis, leading to decreased sperm concentration and motility. These findings support the significance of cytochrome P450 aromatase in human spermatogenesis and consequently in semen quality.

Phosphatidylethanolamine N-methyltransferase and choline dehydrogenase gene polymorphisms are associated with human sperm concentration

Choline is a crucial factor in the regulation of sperm membrane structure and fluidity, and this nutrient plays an important role in the maturation and fertilizing capacity of spermatozoa. Transcripts of phosphatidylethanolamine N-methyltransferase （PEMT） and choline dehydrogenase （CHDH）, two basic enzymes of choline metabolism, have been observed in the human testis, demonstrating their gene expression in this tissue. In the present study, we explored the contribution of the PEMTand CHDHgene variants to sperm parameters. Two hundred oligospermic and 250 normozoospermic men were recruited. DNA was extracted from the spermatozoa, and the PEMT -774G〉C and CHDH ＋432G〉T polymorphisms were genotyped. The genotype distribution of the PEMT-774G〉C polymorphism did not differ between oligospermic and normozoospermic men. In contrast, in the case of the CHDH ＋432G〉T polymorphism, oligospermic men presented the CHDH432GIG genotype more frequently than normozoospermic men （62% vs. 42%, P〈0.001）. The PEMT774GIG genotype was associated with a higher sperm concentration compared to the PEMT774GIC and 774C/C genotypes in oligospermic men （12.5±5.6× 10^6 spermatozoa m1-1 vs. 8.3±5.2×10^6 spermatozoa m1-1, P〈0.002） and normozoospermic men （81.5±55.6×10^6 vs. 68.1±44.5×10^6 spermatozoa m1-1, P〈0.006）. In addition, the CHDH432G/G genotype was associated with higher sperm concentration compared to CHDH432G.T and 432T/T genotypes in oligospermic （11.8±5.1×10^6 vs. 7.8±5.3×10^6 spermatozoa m1-1, P〈0.003） and normozoospermic men （98.6±62.2×10^6 vs. 58.8±＋33.6×10^6 spermatozoa m1-1, P〉0.001）. In our series, the PEMT-774G〈C and CHDH ＋432G〈T polymorphisms were associated with sperm concentration. This finding suggests a possible influence of these genes on sperm quality.