rs10456100 — KCNK5

KCNK5 — The Migraine Threshold Channel

Hidden in an intron of the KCNK5 gene is a common variant that nudges the brain slightly closer to migraine. KCNK5 encodes TASK2¹¹ TASK2
TWIK-related acid-sensitive K+ channel 2 — a two-pore-domain background potassium channel that generates a steady hyperpolarising current to keep neurons just below the firing threshold. Unlike voltage-gated potassium channels that open and close in milliseconds, TASK2 operates as a constitutive "leak" channel — always slightly open, always gently pulling the membrane voltage away from the danger zone. When TASK2 expression falls, that brake weakens.

The Mechanism

rs10456100 sits within an intron of KCNK5 on chromosome 6 (GRCh38 position 39,215,694). The T risk allele acts as an expression quantitative trait locus (eQTL): carriers show significantly lower KCNK5 mRNA levels in subcutaneous adipose tissue (P = 2.70×10⁻¹⁰), and the same directional effect has been observed in brain-relevant tissues. Lower TASK2 expression reduces the background K+ conductance that normally holds neuronal membrane potential in check, meaning neurons are fractionally closer to their depolarisation threshold at rest.

This matters for migraine because cortical spreading depression (CSD)²² cortical spreading depression (CSD)
the slow wave of near-complete depolarisation that sweeps across the cortex and is thought to underlie migraine aura — and to trigger the trigeminovascular pain cascade even in migraine without aura is exquisitely sensitive to background K+ homeostasis. When extracellular K+ rises above ~10 mM — partly due to reduced TASK2-mediated K+ efflux — it can ignite and sustain CSD propagation. KCNK5 also shows strong expression in hippocampal pyramidal neurons and cerebellar granule and Purkinje cells³³ hippocampal pyramidal neurons and cerebellar granule and Purkinje cells, regions where metabolic and ionic shifts during CSD are well-documented.

TASK2 is additionally pH-gated: it activates under alkaline conditions and inhibits under acidic ones. The metabolic acidosis accompanying CSD would suppress TASK2 activity, reducing the K+ recycling that normally terminates the depolarisation wave. T-allele carriers begin with less TASK2 expression to start with, so this failsafe mechanism is further attenuated.

The Evidence

The largest genetic evidence comes from Hautakangas et al. 2022⁴⁴ Hautakangas et al. 2022
Genome-wide analysis of 102,084 migraine cases identifies 123 risk loci. Nature Genetics, which identified rs10456100-T as one of 123 genome-wide significant migraine loci (OR = 1.052, P = 9.0×10⁻¹⁹). The T allele is common — about 28% of the global population carries at least one copy — and the per-allele effect is modest but robustly replicated.

Earlier GWAS meta-analyses confirmed this signal: Gormley et al. 2016⁵⁵ Gormley et al. 2016
Nature Genetics, with 59,674 cases, reported OR = 1.06 at P = 7×10⁻¹³ at this locus. The KCNK5 locus has now been replicated independently in European, Han Chinese, and Latin American cohorts, establishing it as one of the most consistently replicated non-CGRP migraine risk loci.

A Han Chinese study (Zhang et al. 2021, Scientific Reports)⁶⁶ (Zhang et al. 2021, Scientific Reports) confirmed the T allele association with migraine without aura in two independent Chinese samples (P = 9.0×10⁻⁹ in discovery, replicated), and demonstrated the adipose eQTL specifically, suggesting the intronic variant affects a regulatory element controlling KCNK5 transcription.

Practical Actions

For T allele carriers, the practical implication is a slightly lower migraine threshold — the threshold is not fixed, and several modifiable factors interact with neuronal excitability to shift it up or down. Magnesium stabilises NMDA receptors and reduces cortical hyperexcitability; riboflavin (vitamin B2) supports mitochondrial energy production, which is critical for maintaining ion gradients (including K+) across neuronal membranes. Both have specific evidence in migraine prevention and are more directly relevant for a K+-channel variant than generic anti-inflammatory approaches.

Sleep deprivation and irregular sleep are among the strongest environmental triggers of CSD-susceptibility, likely because K+ homeostasis during sleep differs substantially from wakefulness — the glymphatic system and K+ clearance mechanisms operate differently in NREM sleep, and abrupt disruptions elevate cortical excitability.

Interactions

KCNK5 belongs to the two-pore-domain K+ channel superfamily, which also includes KCNK18 (TRESK), a channel in which a rare frameshift mutation causes familial migraine with aura. The TRESK and TASK2 channels share complementary roles in regulating trigeminal neuron excitability — variants in both genes converge on the same threshold-setting mechanism. The GWAS catalog also notes a pleiotropic association between rs10456100-T and coronary artery disease risk (van der Harst 2017), potentially reflecting TASK2 expression in vascular or immune cells; the mechanistic basis for this pleiotropy is not yet established.