The Arg753Gln Polymorphisms in Toll-like Receptor 2 in a Syphilis-Infected and Control Population in The Netherlands: Can Differences in the Number of Self-Reported Sexual Contacts Indicate Protection against Syphilis?

The Arg753Gln polymorphism in Toll-like receptor 2 has been associated with an increased risk of bacterial infections as well as with protection from the late stages of Lyme disease and the acquisition of syphilis. In this study, we determined the presence of this polymorphism in samples collected from men having sex with men/men with women in the Amsterdam Cohort Studies. The presence of the polymorphism was determined by nested PCR, followed by Sanger sequencing. A set of 90 syphilis-seronegative individuals was compared to 95 syphilis-diagnosed participants. A polymorphism allele frequency of 3.9% was found in the control group and 2.63% in the syphilis case group, respectively. None of the individuals showed a homozygous Arg753Gln polymorphism. The number of self-reported sexual contacts was higher in the group of syphilis patients compared to the control group (p = 0.0063). Moreover, in the syphilis case group (n = 49), participants heterozygous for the TLR2-Arg753Gln reported higher numbers of sexual contacts (p = 0.037) compared to wild-type homozygotes. Our findings suggest a possible protective effect of TLR2-Arg753Gln in the acquisition of syphilis. In addition, the determination of the number of self-reported sexual contacts can be used in an evaluation of the protective effect of polymorphism in a population with a low prevalence of it.