Respiratory sinus arrhythmia and serotonin transporter promoter gene polymorphisms: Taking a triallelic approach makes a difference

AbstractIt has been recently reported in Psychophysiology that carriers of the short allele of an insertion/deletion (ins/del) functional polymorphism in the promoter region (5‐HTTLPR) of the serotonin transporter gene may display decreased resting respiratory sinus arrhythmia (RSA). However, this region hosts another functionally connected single‐nucleotide polymorphism (rs25531), which should also be genotyped in order to correctly categorize the low‐ and high‐expressing alleles of 5‐HTTLPR. The present study investigated resting RSA in an ethnically homogenous sample (N = 143) of participants genotyped for both the ins/del and rs25531 polymorphisms in 5‐HTTLPR. In contrast with the biallelic genotypes, based only on the ins/del alleles, the triallelic 5‐HTTLPR genotypes (i.e., including rs25531) showed no association with resting RSA. Taking a triallelic approach to 5‐HTTLPR is thus necessary in order to avoid false positive results.