The Association between the 5-HTTLPR Polymorphism of the Serotonin Transporter Gene with the Development of Somatoform Disorder in Children

The purpose of the study is to reveal the association of 5-HTTLPR polymorphism, including the
single nucleotide polymorphism rs25531 (A/G) of the polymorphic region of the L-allele, with the
risk of development of somatoform disorder (SD) in children.
Materials and methods. There were examined 94 children with SD. The average age of children
was 13.4±2.1 years. The control group consisted of 32 children. Serum serotonin was determined
with a biochemical method. Genetic polymorphism was determined with PCR.
Results. In children with SD, the S/S 5-HTTLPR polymorphism is 1.5 times more common and the
S/L polymorphism is 1.9 times less frequent than in children without SD. The average serotonin level
in children with SD was 1.16±0.37 μmol/l, in children without SD – 1.35±0.34 μmol/l (p<0.012). The level of serotonin in children with SD and the presence of S/S allele was 1.15±0.39 μmol/l, and it was lower, if compared to children without SD (p<0,014). Serotonin levels in children with SD and S/L were 1.24±0.34 μmol/l. High-expressing 5-HTT rs25531 (A/G) polymorphism of LA/LA in children with SD was 2.9 times less frequent, if compared with children, who did not have SD; and the averageexpressing 5-HTT polymorphism S/LA – 1.7 times less frequent. Conclusion. The risk of development of SD with the presence of S/S allele increases by 2.96 times (odds ratio – OR 2.96±0.42, where 95% CI, 1.29–6.78). The risk of development of SD with the presence of S/L allele decreases by 0.37 times (OR 0.37±0.43; 95% CI, 0.16–0.86). The presence of the S/S allele may be a factor of impaired serotonin metabolism and, accordingly, increase the risk of SD and comorbid depression and anxiety.