Biallelic and Triallelic 5-Hydroxytyramine Transporter Gene-Linked Polymorphic Region (5-HTTLPR) Polymorphisms and Their Relationship with Lifelong Premature Ejaculation: A Case-Control Study in a Chinese Population

BACKGROUND This study aimed to explore the relationship between premature ejaculation (PE) and the serotonin transporter gene-linked polymorphic region (5-HTTLPR) with respect to the biallelic and triallelic classifications. MATERIAL AND METHODS A total of 115 outpatients who complained of ejaculating prematurely and who were diagnosed as having lifelong premature ejaculation (LPE) and 101 controls without PE complaint were recruited. All subjects completed a detailed questionnaire and were genotyped for 5-HTTLPR polymorphism using PCR-based technology. We evaluated the associations between 5-HTTLPR allelic and genotypic frequencies and their association with LPE, as well as the intravaginal ejaculation latency time (IELT) of different 5-HTTLPR genotypes among LPE patients. RESULTS The patients and controls did not differ significantly in terms of any characteristic except age. The results showed no significant difference regarding biallelic 5-HTTLPR. According to the triallelic classification, no significant difference was found when comparing the genotypic distribution (P=0.091). However, the distribution of the S, LG, and LA alleles in the cases was significantly different from the controls (P=0.018). We found a significantly lower frequency of LA allele and higher frequency of LG allele in patients. Based on another classification by expression, we found a significantly lower frequency of the L'L' genotype (OR=0.37; 95%CI=0.15-0.91, P=0.025) in patients with LPE. No significant association was detected between IELT of LPE and different genotypes. CONCLUSIONS Contrary to the general classification based on S/L alleles, triallelic 5-HTTLPR was associated with LPE. Triallelic 5-HTTLPR may be a promising field for genetic research in PE to avoid false-negative results in future studies.