BTBD9 rs1138562: What Your Genotype Means
The rs1138562 variant is a common genetic change located within the BTBD9 gene. It has been identified in research studies as being associated with an increased likelihood of experiencing Restless Legs Syndrome (RLS) and periodic limb movements in sleep (PLMS).
What each genotype means
Typical baseline risk
You carry two copies of the non-risk A allele for this BTBD9 marker. Studies show that individuals with this genotype do not carry the elevated statistical risk for periodic limb movements in sleep (PLMS) or restless legs syndrome (RLS) linked to the alternative allele. However, lifestyle, iron status, and other genetic determinants still influence overall sleep and movement characteristics.
Carried by approximately 25% to 30% of individuals of European ancestry and at varying frequencies across other global populations.
Moderately increased PLMS risk
You carry one copy of the G risk allele at rs1138562 in the BTBD9 gene. In population association studies, carrying one risk allele is linked to a moderate increase in the likelihood of periodic limb movements during sleep (PLMS) and restless legs syndrome (RLS). This variant represents a subtle statistical risk factor rather than a medical diagnosis, and many carriers experience normal sleep.
Carried by approximately 45% to 50% of individuals of European ancestry.
Higher PLMS risk
You carry two copies of the G risk allele for rs1138562 within the BTBD9 gene. Research indicates that homozygous carriers have a higher statistical likelihood of frequent periodic limb movements in sleep (PLMS) and restless legs syndrome compared to non-carriers. Genetic susceptibility alone does not guarantee symptoms, as non-genetic factors such as peripheral iron stores also play a substantial role.
Found in approximately 20% to 25% of individuals of European ancestry.
Understanding the rs1138562 Variant
The rs1138562 variant is a single nucleotide polymorphism (SNP) located within the BTBD9 gene. In genetics, a SNP represents a variation at a single position in the DNA sequence. This specific variant is found in an intronic region, meaning it sits within a non-coding part of the gene that does not provide direct instructions for building a protein. However, intronic variants can still influence how genes are regulated or expressed. Because this variant is common in many populations, it is considered a normal part of human genetic diversity rather than a rare mutation. Researchers study such variants to understand how subtle differences in our DNA might contribute to complex traits or susceptibility to certain health conditions, rather than acting as a direct cause of disease.
The Role of the BTBD9 Gene
The BTBD9 gene, which stands for BTB domain-containing 9, provides instructions for producing a protein whose exact biological function is still being investigated. The BTB domain is a structural motif often involved in protein-protein interactions and the regulation of gene expression. Research suggests that BTBD9 is expressed in various tissues, including the brain, where it may play a role in neurological processes. Studies using animal models, such as mice, have shown that the absence of the BTBD9 gene can lead to behaviors resembling motor restlessness and sleep disturbances. These findings have led scientists to hypothesize that the gene may be involved in dopaminergic signaling—a system that helps control movement—and iron metabolism, both of which are relevant to the study of sleep-related movement disorders.
Research Associations and Evidence Strength
The association between BTBD9 variants and sleep-related conditions is supported by genome-wide association studies (GWAS). These studies compare the DNA of individuals with specific traits, such as Restless Legs Syndrome (RLS) or periodic limb movements in sleep (PLMS), against those without them. While rs1138562 and other nearby variants in the BTBD9 gene show a statistical correlation with these conditions, the evidence is considered limited in terms of clinical predictability. This means that while the variant is more common in people with these sleep traits, it is not a diagnostic tool. Many people who carry the variant do not have RLS, and many people with RLS do not carry the variant. The link is likely part of a complex interplay involving multiple genetic factors, environmental influences, and lifestyle variables.
Population Frequency
The rs1138562 variant is a common genetic marker. In populations of European ancestry, the minor allele frequency (MAF) typically ranges between 0.45 and 0.50. This high frequency indicates that a large portion of the population carries at least one copy of the variant. Because it is so common, it is classified as a widespread polymorphism. When a variant is this frequent, it is generally expected that it does not cause severe, rare diseases on its own, as such variants would likely be subject to stronger evolutionary pressure. Instead, it is viewed as a contributor to common, complex traits where many different genetic and environmental factors combine to influence an individual's risk profile.
Interpreting Your Genetic Information
It is important to understand that genetic associations are statistical observations made across large groups of people, not personal medical predictions. Having a specific genotype for rs1138562 does not mean you will develop a sleep disorder, nor does the absence of it guarantee you will not. Sleep quality is influenced by a wide array of factors, including iron levels, medication use, caffeine intake, and other underlying health conditions. If you are concerned about your sleep patterns, such as experiencing an irresistible urge to move your legs or repetitive limb movements at night, you should consult a healthcare professional. They can provide a proper clinical evaluation, which is far more informative than any single genetic variant. Never use genetic information to self-diagnose or alter your medical treatment without professional guidance.
How common is this variant?
This is a common variant with a minor allele frequency of approximately 0.45-0.50 in populations of European ancestry.
Frequently asked questions
Does having the BTBD9 variant mean I have Restless Legs Syndrome?
No. The variant is associated with a statistical increase in risk across large populations, but it is not a diagnostic test for RLS. Many people with the variant do not have the condition.
Can I use this information to prevent sleep disorders?
Genetic information for this variant cannot be used to predict or prevent sleep disorders. Lifestyle factors like maintaining healthy iron levels and good sleep hygiene are generally more significant for sleep health.
Is this variant considered a mutation?
In genetics, this is classified as a common polymorphism rather than a rare mutation. It is a normal variation found in a large percentage of the healthy population.
Should I talk to my doctor about my BTBD9 genotype?
If you are experiencing symptoms like sleep disturbances or leg discomfort, you should discuss these symptoms with your doctor. They will focus on your clinical history rather than your genetic test results.
Sources & further reading
Educational information only, last refreshed 9/12/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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This variant in the BTBD9 gene is strongly associated with susceptibility to restless legs syndrome (RLS).
Intronic variant strongly associated with restless legs syndrome (RLS) susceptibility and periodic limb movements during sleep (PLMS), mediating altered iron homeostasis.
A prominent non-coding variant in BTBD9 strongly conferring risk for periodic limb movements during sleep and restless legs syndrome.
Genome-wide significant intronic susceptibility variant in BTBD9 strongly predisposing individuals to restless legs syndrome and periodic limb movements in sleep.
A regulatory intron variant in BTBD9 strongly associated with periodic limb movements in sleep.
Common non-coding regulatory variant in BTBD9 influencing restless legs syndrome risk and periodic leg movements during sleep.