Alu-repeat polymorphism in the tissue plasminogen activator (t-PA) gene, seminal t-PA concentration, and male fertility impairment: A case-control study

Background: Tissue plasminogen activator (t-PA) is a protein involved in the fibrinolytic system that catalyzes the conversion of plasminogen into the active plasmin. The activity of t-PA is controlled by plasminogen activator inhibitor-1. t-PA has crucial functions during spermatogenesis. One polymorphism was reported for t-PA gene, either the presence of a 300-bp Alu-repeat (Alu ${}^{+}$ ) or its absence (Alu ${}^{-}$ ).

Objective: The current work aimed at studying the association between Alu polymorphism in the t-PA gene and male infertility.

Materials and methods: Using polymerase chain reaction on genomic DNA isolated from the blood of 79 participants, a region polymorphic for Alu element insertion in t-PA gene was amplified. In addition, total t-PA concentration, plasminogen activator inhibitor-1 /t-PA complex concentration, and t-PA activity in seminal plasma were measured by enzyme-linked immunosorbent assay.

Results: The results indicate that the percentage of infertile participants (n = 50) who were homozygous for t-PA Alu insertion (Alu ${}^{+/+}$ ), heterozygous Alu ${}^{+/-}$ or homozygous for t-PA Alu deletion (Alu ${}^{-/-}$ ) did not change significantly (p = 0.43, 0.81, and 0.85, respectively) when compared with the control participants (n = 29). On the other hand, a significant decrease (p = 0.0001) of t-PA total concentration in seminal plasma was observed in the infertile group in comparison with the control group. However, the results indicate that there is no association between the t-PA Alu different genotypes and the total t-PA seminal concentration in the infertile group when compared to the control group (p = 0.63).

Conclusion: Data obtained from the current study does not support an association between t-PA Alu polymorphism and t-PA seminal concentration or male infertility.