A common neurological sleep-related movement disorder causing an overwhelming urge to move the legs, worse at rest and in the evening and relieved by movement, which fragments sleep and often runs in families.
Restless legs syndrome (RLS), also called Willis-Ekbom disease, is a neurological disorder in which a person feels an urgent, almost irresistible need to move their legs. The urge is usually accompanied by an uncomfortable sensation deep inside the legs that people describe in strikingly varied ways — crawling, creeping, pulling, tugging, aching, fizzing or an itch that cannot be scratched. It is not the same as ordinary restlessness, cramp or pins and needles, and people who have it often struggle to put the feeling into words.
What makes restless legs syndrome distinctive is its pattern rather than the sensation itself. Symptoms appear or worsen when a person is sitting still or lying down, they get worse in the evening and at night, and they are at least partly relieved by moving — walking, stretching, rubbing the legs or getting out of bed. That relief lasts only as long as the movement does, which is why the condition is so effective at destroying sleep. The arms and other body parts can be affected too, usually later in the illness and usually after the legs.
The main consequence is chronic sleep loss. Falling asleep takes longer, sleep is broken, and the resulting daytime tiredness, difficulty concentrating and low mood are frequently what drives people to seek help rather than the leg sensations themselves. Many people with restless legs syndrome also have periodic limb movements during sleep — repetitive, involuntary jerks of the legs that they may be unaware of but that a bed partner notices.
Restless legs syndrome is common. It affects an estimated 5 to 10 percent of adults in the United States and 2 to 4 percent of children, though only a minority have symptoms severe or frequent enough to need treatment. It is roughly twice as common in women as in men, and it becomes both more frequent and more severe with age. Symptoms can begin at any age, including childhood, where they are sometimes mistaken for growing pains or attention problems.
Two things stand out about its causes. The first is iron. Restless legs syndrome is closely connected to how much iron is available in the brain, and importantly, brain iron can be low even when someone is not anaemic and their blood iron looks acceptable. Iron is needed to make dopamine, a chemical messenger involved in controlling movement, and the leading explanation for restless legs syndrome involves disturbed iron handling in specific brain regions with knock-on effects on dopamine signalling. This is why doctors routinely check iron studies in anyone with troublesome symptoms.
The second is heredity. Restless legs syndrome runs in families to an unusual degree for a common condition — depending on the study, somewhere between 40 and 90 percent of affected people report an affected first-degree relative, and people with a family history tend to develop symptoms earlier. Some families show a pattern that looks like simple dominant inheritance, but in most people the pattern is not simple, and the genetic contribution comes from many common variants each adding a small amount of risk. The MEIS1 variant linked on this page is the single strongest and most reliably replicated of them.
Restless legs syndrome can also appear or worsen alongside other conditions and exposures: iron deficiency, pregnancy (particularly the third trimester, after which symptoms usually settle), advanced kidney disease and dialysis, and peripheral neuropathy. A number of widely used medicines can provoke or aggravate it, including sedating antihistamines, anti-nausea and antipsychotic drugs that block dopamine, and many antidepressants. Caffeine, nicotine and alcohol commonly make symptoms worse.
There is no blood test or scan that diagnoses restless legs syndrome. It is diagnosed clinically, from the history, using a set of agreed criteria — and a key part of that assessment is deliberately ruling out the many conditions that can imitate it, such as night cramps, simple positional discomfort, nerve damage, varicose veins and drug-induced akathisia. Blood tests are done not to confirm the diagnosis but to check iron status and look for contributing conditions.
On genetics: the MEIS1 variant described here comes from genome-wide association research. It is a common variant, found on about a quarter of chromosomes in people of European ancestry — an allele frequency near 0.24, meaning roughly two in five people carry at least one copy — and while its effect is unusually strong by the standards of such studies, it is still a risk-modifying variant and not a cause. It cannot diagnose the condition, cannot rule it out, and is not used in clinical care.
Restless legs syndrome / Willis-Ekbom disease is diagnosed clinically using the International Restless Legs Syndrome Study Group (IRLSSG) consensus criteria, revised in 2012. All five essential criteria must be met: (1) an urge to move the legs, usually but not always accompanied by uncomfortable and unpleasant leg sensations; (2) the urge begins or worsens during periods of rest or inactivity; (3) it is partially or totally relieved by movement, at least for as long as the movement continues; (4) it occurs only in the evening or night, or is worse then; and (5) the features are not solely accounted for by another condition or behavioural state. That fifth criterion was added in the 2012 revision specifically to improve specificity by forcing exclusion of mimics — leg cramps, positional discomfort, myalgia, venous stasis, peripheral neuropathy, habitual foot tapping and neuroleptic-induced akathisia.
The 2012 revision also introduced a clinical-significance specifier (symptoms causing distress or impairment in sleep, mood, cognition or daily function), course specifiers distinguishing chronic-persistent from intermittent disease, and a merging of the previously separate paediatric criteria into the adult set. Supportive features that increase diagnostic confidence include a positive family history, periodic limb movements of sleep on polysomnography, and historical responsiveness to dopaminergic therapy; none is required. Polysomnography is not needed for routine diagnosis and is reserved for cases where a comorbid sleep disorder is suspected or where objective quantification of periodic limb movements is required.
Evaluation should include iron studies. IRLSSG task force guidance recommends measuring serum ferritin together with transferrin saturation, drawn in the morning and off iron-containing supplements and foods for at least 24 hours beforehand, since ferritin is an acute-phase reactant and diurnally variable. Their consensus thresholds for considering iron supplementation in adults are serum ferritin at or below 75 ng/mL or transferrin saturation below 20% (oral or intravenous iron), and ferritin between 75 and 100 ng/mL (intravenous iron only); in children the threshold is ferritin below 50 ng/mL. These consensus thresholds have not been formally validated in trials, and serum iron indices do not reliably predict who will respond.
Secondary and comorbid associations to consider include iron deficiency with or without anaemia, end-stage renal disease and dialysis, pregnancy, and peripheral neuropathy. Exacerbating agents include sedating H1 antihistamines, dopamine-receptor antagonists (antipsychotics, metoclopramide, prochlorperazine) and most serotonergic and noradrenergic antidepressants, with bupropion generally considered the least likely to aggravate symptoms.
The dominant model is regional brain iron insufficiency — demonstrated in cerebrospinal fluid, imaging and autopsy studies, particularly in the substantia nigra — occurring in many patients despite normal systemic iron indices, with downstream dysregulation of nigrostriatal dopaminergic signalling. Adenosinergic and glutamatergic hypotheses have gained ground as complementary explanations, particularly for the hyperarousal and sleep-onset features. The condition is classified as a sleep-related movement disorder and is coded in ICD-10-CM as G25.81.
Restless legs syndrome is polygenic. Schormair and colleagues (2017, Lancet Neurology) meta-analysed genome-wide data on 15,126 cases and 95,725 controls of European ancestry with replication in a further 30,770 cases and 286,913 controls, identifying 13 new loci and confirming the six previously known, for 19 in total. Prioritised pathways centred on neurodevelopment — axon guidance, synapse formation and neuronal specification. That study explicitly confirmed MEIS1 as the strongest genetic risk factor for the condition, with an odds ratio of 1.92 (95% CI 1.85–1.99) at the locus.
rs2300478 (MEIS1, 2p14). This intronic variant sits in MEIS1, a TALE-family homeobox transcription factor gene with established roles in limb and neural development. It was among the signals from the first restless legs syndrome GWAS, by Winkelmann and colleagues (2007, Nature Genetics), which studied 401 European-ancestry cases and 1,644 controls with replication in independent European and French-Canadian cohorts, and which implicated MEIS1, BTBD9 and the MAP2K5/SKOR1 (LBXCOR1) region. The GWAS Catalog records for that study a risk allele of G at a frequency of about 0.24, with an odds ratio of 1.74 (95% CI 1.57–1.92) and p = 3 × 10-28.
The signal has replicated with unusual consistency. In Winkelmann and colleagues' larger 2011 study (PLoS Genetics; 922 cases / 1,526 controls with replication in 3,935 cases / 5,754 controls, all European ancestry) the same SNP gave OR = 1.68 (95% CI 1.57–1.81) at p = 3 × 10-49. An exome-chip study by Tilch and colleagues (2022) in 3,652 cases and 5,360 controls again returned a comparable effect, OR ≈ 1.60 (95% CI 1.49–1.73), p = 1 × 10-35. Independent candidate-gene replications in a US population and in Czech, Austrian and Finnish samples reported odds ratios in the same range. An effect of roughly 1.6–1.75 per allele is large for a common variant identified by genome-wide association — considerably larger than the typical complex-trait GWAS hit — which is why MEIS1 is consistently described as the flagship restless legs syndrome susceptibility locus.
Functional work indicates the risk haplotype is associated with reduced MEIS1 expression, and model-organism studies have connected reduced MEIS1 function to motor restlessness and to altered iron homeostasis, which fits the iron-dopamine model. The precise causal variant within the associated haplotype block and the definitive mechanism have not been fully resolved.
Despite its comparatively strong effect, rs2300478 remains a common risk-modifying polymorphism and not a deterministic mutation. The risk allele is carried by a substantial minority of the general European-ancestry population, the great majority of whom do not have restless legs syndrome, and MEIS1 together with all currently known loci accounts for only a small share of the condition's heritability. The variant has no diagnostic, predictive or therapeutic role in clinical practice; diagnosis remains entirely clinical, by the IRLSSG criteria. Reported effect estimates derive almost exclusively from European-ancestry cohorts and should not be assumed to transfer to other populations.
For completeness on treatment context rather than as guidance: the American Academy of Sleep Medicine's 2025 clinical practice guideline reversed longstanding practice by issuing conditional recommendations against the routine use of the dopamine agonists pramipexole and ropinirole, because of augmentation — a progressive worsening and earlier daily onset of symptoms with sustained dopaminergic treatment — and gave strong recommendations to the alpha-2-delta ligands gabapentin enacarbil, gabapentin and pregabalin, and to intravenous ferric carboxymaltose. Treatment decisions belong with a clinician; genotype plays no part in them.
What a 23andMe/AncestryDNA export or raw VCF can and can't tell you about Restless Legs Syndrome comes down to these specific, well-studied positions — not a diagnosis.
No. The risk allele sits on roughly a quarter of chromosomes in people of European ancestry (a frequency near 0.24), which works out to about two in five people carrying at least one copy — and the large majority of them never develop restless legs syndrome. Its effect — an odds ratio of about 1.6 to 1.75 per copy — is unusually strong for a variant found by genome-wide association research, but it still only shifts probability. Restless legs syndrome is diagnosed from symptoms using clinical criteria, never from a genetic test.
Because it has replicated more consistently and with a larger effect than any other locus. The same variant produced comparable odds ratios across independent European cohorts in 2007, 2011 and 2022, and a large 2017 meta-analysis of over 45,000 cases confirmed MEIS1 as the strongest signal, with an odds ratio of 1.92 at the locus. Even so, MEIS1 and all the other known loci together explain only a small share of why the condition runs in families.
Iron is needed to produce dopamine, the brain chemical that helps regulate movement, and the leading model of restless legs syndrome is that specific brain regions are short of iron. Crucially, this can happen even when someone is not anaemic and their routine blood counts look normal, which is why clinicians check ferritin and transferrin saturation specifically. Laboratory work on MEIS1 has also linked reduced gene function to altered iron handling, which is one reason the genetic and iron explanations fit together.
Entirely from the clinical history, using the five essential IRLSSG criteria: an urge to move the legs, worsening at rest, relief with movement, an evening or night-time pattern, and — added in the 2012 revision — confirmation that the symptoms are not better explained by something else. That last criterion matters, because cramps, positional discomfort, nerve damage, varicose veins and drug-induced restlessness can all imitate the condition. Blood tests are done to check iron status and look for contributing conditions, not to make the diagnosis.
Yes, and this is a common and often overlooked cause of worsening. Sedating antihistamines, dopamine-blocking anti-nausea and antipsychotic medicines, and most antidepressants can provoke or aggravate symptoms. Caffeine, nicotine and alcohol frequently do too. Anyone whose symptoms have worsened after starting a new medicine should raise it with the prescribing clinician rather than stopping the medicine on their own.
Free to reuse. This page's text is original writing from freely-available research, licensed CC BY 4.0 — reuse it, including commercially, with attribution to MyGeneLog. It's general research-derived information, not medical advice or a diagnosis — see Terms of Use.