Leadership personality type

A leadership personality type occurs in individuals with two long forms of transporter region (5-HTTLPR) of the serotonin transporter gene.

5-HTTLPR (serotonin-transporter-linked polymorphic region) is a degenerate repeat polymorphic region in SLC6A4, the gene that codes for the serotonin transporter. Since the polymorphism was identified in the middle of the 1990s, it has been extensively investigated, e.g., in connection with neuropsychiatric disorders. A 2006 scientific article stated that "over 300 behavioral, psychiatric, pharmacogenetic and other medical genetics papers" had analyzed the polymorphism.

Alleles
The polymorphism occurs in the promoter region of the gene. Researchers commonly report it with two variations: A short ("s") and a long ("l"), but it can be subdivided further. In connection with the region are two single nucleotide polymorphisms (SNP): rs25531 and rs25532.

One study published in 2000 found 14 allelic variants (14-A, 14-B, 14-C, 14-D, 15, 16-A, 16-B, 16-C, 16-D, 16-E, 16-F, 19, 20 and 22) in a group of around 200 Japanese and Caucasian people. The difference between 16-A and 16-D is the rs25531 SNP. It is also the difference between 14-A and 14-D.

Some studies have found that long allele results in higher serotonin transporter mRNA transcription in human cell lines. The higher level may be due to the A-allele of rs25531, such that subjects with the long-rs25531(A) allelic combination (sometimes written LA) have higher levels while long-rs25531(G) carriers have levels more similar to short-allele carriers. Newer studies examining the effects of genotype may compare the LA/LA genotype against all other genotypes. The allele frequency of this polymorphism seems to vary considerably across populations, with a higher frequency of the long allele in Europe and lower frequency in Asia.

Personality traits
In a recent study, authors found that individuals homozygous for the long allele of 5-HTLPR paid more attention on average to positive affective pictures while selectively avoiding negative affective pictures presented alongside the positive pictures compared to their heterozygous and short-allele-homozygous peers. This biased attention of positive emotional stimuli suggests they may tend to be more optimistic. Other research indicates carriers of the short 5-HTTLPR allele have difficulty disengaging attention from emotional stimuli compared to long allele homozygotes. Another recent study using an eye tracking assessment of information processing found that short 5-HTTLPR allele carriers displayed an eye gaze bias to view positive scenes and avoid negative scenes. Long allele homozygotes viewed the emotion scenes in a more even-handed fashion. This research suggests that short 5-HTTLPR allele carriers may be more sensitive to emotional information in the environment than long allele homozygotes.