What this means

KLB encodes β-Klotho, a co-receptor for the liver hormone FGF21. FGF21 is released by the liver after drinking and acts in the brain to dampen the reward signal from alcohol — essentially a "you've had enough" message from gut to brain. rs11940694 sits in the KLB locus and emerged from a UK Biobank GWAS of self-reported alcohol intake (Schumann et al., PNAS 2016, n ≈ 105,000), since replicated in larger meta-analyses including GSCAN. The G allele is associated with modestly lower consumption. The mechanism — a hormonal brake on the reward of drinking — is one of the cleanest stories in alcohol genetics.

KLB makes part of a receptor that lets your liver talk to your brain after a drink. When you drink, your liver sends a signal that basically says "that's enough", and the brain dials down how rewarding the next drink feels. One common DNA change at this gene nudges that signal up or down a little. People with the dialled-up version report drinking somewhat less; people with the dialled-down version report drinking somewhat more. The effect on any one person is small — habits, friends, mood and culture matter much more — but it's one of the clearest GWAS findings for alcohol consumption.

Caveats

• The effect size on individual consumption is small. Habits, environment, and mood dwarf it.
• The variant predicts average self-reported intake, not problem drinking.
• Self-reported alcohol intake is noisy; effect estimates likely under-state the biology.
• This is a brain-side finding — it's about wanting another drink, not about how your body metabolises alcohol.

Populations

• Studied in UK Biobank and meta-analyses across European, East Asian, and African ancestries

References

• Schumann et al. — KLB is associated with alcohol drinking, and its gene product β-Klotho is necessary for FGF21 regulation of alcohol preference (PNAS, 2016)
• Liu et al. — Association studies of up to 1.2 million individuals yield new insights into the genetic etiology of tobacco and alcohol use (Nature Genetics, 2019)