rs79874540

A SNP in the HTR2B gene on chromosome 2. Its most notable genotype is A;G: 2-3 fold higher risk of impulsive/aggressive behaviour when drunk

Gene
HTR2B
Location
Chr 2231,123,707 (GRCh38)
Highest magnitude
3.3Important
Tested on
23andMe
Minor allele frequency
<1%

Genotypes

Plus strand, as in 23andMe and AncestryDNA files.

  1. G;GGoodcommon in complete genomicsTypical · 0.0
  2. A;GMost notableBad2-3 fold higher risk of impulsive/aggressive behaviour when drunkImportant · 3.3
  3. A;ABadIncreased risk for impulsive/aggressive behaviour when drunkImportant · 3.3

SNPedia records rs79874540 on the minus strand: (C;C), (C;T), (T;T). Magnitude rates how notable a genotype is from 0 to 10, not how risky it is.

Conditions, medicines and genes

Notes

From SNPedia

Show notes, about 210 words

rs79874540, known in the literature primarily as Q20* or Q20X, represents an uncommon variant in the HTR2B gene on chromosome 2 found almost exclusively in those of Finnish origin. A 2010 paper concluded that the rs79874540(T) variant, carried by 2.2% of the population in Finland, was associated with somewhat (2 - 3 fold?) increased risk for impulsive and/or aggressive behaviour, especially when under the influence of alcohol. The number of men studied was not particularly high. A 2015 follow-up study using a personality questionnaire by the same researchers of 14 heterozygous HTR2B Q20* carriers and 156 healthy controls lacking HTR2B Q20* reinforced the "aggressive when drunk" association for the Q20* allele carriers, but also noted that the Q20* carriers were neither alcoholics per se (as measured by average alcohol consumption) nor diagnosed as alcoholics, even if they had a tendency to lose behavioral control while under the influence of alcohol. In 2016, other Finnish researchers observed that at least for Finnish males having an antisocial personality disorder, Q20* carriers who also had low or normal testosterone levels were at lower risk for obesity than non-carriers.

A;G

See discussion at rs79874540

A;A

see discussion at rs79874540

Source and license

Adapted from rs79874540 on SNPedia, using a snapshot taken October 16, 2026. SNPedia content is shared under CC BY-NC-SA 3.0 US, and this page is shared under the same license.

SNPedia is a community-edited wiki. Its entries can be incomplete, out of date or wrong, and nothing here is a diagnosis or medical advice. Magnitude is a community rating of how interesting a genotype is, not a risk score.