Serotonin transporter gene polymorphisms in patients with chronic tension-type headache: A preliminary study

Background and Objectives: This study is designed to understand the pathophysiology of one of the most serious health problems, chronic tension-type headache (CTTH). Two polymorphic sites in serotonin transporter protein gene attracted much interest. These are: the variable number of tandem repeats (VNTR) and 5′-flanking promoter region (5-HTTLPR).
Materials and Methods: VNTR and 5-HTTLPR polymorphisms were investigated in 126 CTTH patients and 138 healthy control subjects. The patients were being treated with amitripytyline or citalopram or sertraline (SSRI). The polymerase chain reaction (PCR) method was used to investigate the polymorphisms in the serotonin transporter protein gene.
Results: There were no statistically significant results based on the 5-HTTLPR gene alleles, however, STin 2.12/12 genotype and STin 2.12 allele were seen to predominate the control group. In order to investigate the combined effect of the two polymorphic loci on the 5-HTT gene expression, samples were separated into nine groups. Genotypes (S/S-12/10) and (L/S-12/10) displayed statistically significant frequency in the CTTH group than in the control group. No significant differences were noticed between the 5-HTTLPR and VNTR haplotype groups and success in treatment.
Conclusion: It is possible to make reliable comparisons and hypothesis about the homozygous and/or heterozygous presence of S and STin 12/10 alleles which may be in interaction with CTTH. On the other hand, the presence of homozygous L and STin12 alleles may play a protective role against CTTH. It is also possible that heterogeneity among diseases showing the same clinical research will require a lot of effort for individual identification.

Keywords
5-flanking promoter region, chronic tension-type headache, haplotypes, serotonin transporter protein gene, a variable number of tandem repeats