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 PEMT and CHDH gene 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 CHDH 432G/G genotype more frequently than normozoospermic men (62% vs. 42%, P<0.001). The PEMT 774G/G genotype was associated with a higher sperm concentration compared to the PEMT 774G/C and 774C/C genotypes in oligospermic men (12.5 ± 5.6 × 10(6) spermatozoa ml(-1) vs. 8.3 ± 5.2 × 10(6) spermatozoa ml(-1), P<0.002) and normozoospermic men (81.5 ± 55.6 × 10(6) vs. 68.1 ± 44.5 × 10(6) spermatozoa ml(-1), P<0.006). In addition, the CHDH 432G/G genotype was associated with higher sperm concentration compared to CHDH 432G/T and 432T/T genotypes in oligospermic (11.8 ± 5.1 × 10(6) vs. 7.8 ± 5.3 × 10(6) spermatozoa ml(-1), P<0.003) and normozoospermic men (98.6 ± 62.2 × 10(6) vs. 58.8 ± 33.6 × 10(6) spermatozoa ml(-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.