PER3 rs1012477: What Your Genotype Means
The rs1012477 variant is a single nucleotide polymorphism located within the PER3 gene, which is essential for maintaining the body's internal circadian clock. Research has explored its potential associations with circadian rhythm regulation and breast cancer risk, particularly in pre-menopausal women.
What each genotype means
Typical circadian preference
This genotype represents the most common form of this variant in many populations. Research suggests this variant is associated with variations in diurnal preference, though the evidence linking this specific SNP to sleep timing is considered limited and may vary by ancestry.
This is the most frequent genotype observed in most global populations.
Varied circadian preference
Carrying one copy of the C allele may be associated with subtle differences in chronotype or diurnal preference compared to the GG genotype. Because the evidence for this association is limited, it is unclear how significantly this genotype influences individual sleep-wake patterns.
This heterozygous genotype is found at moderate frequencies across diverse populations.
Potential circadian variation
This genotype is associated with potential shifts in diurnal preference in some studies, though findings are not consistent across all research cohorts. As the evidence is limited, this genotype should not be used to predict specific sleep behaviors or diagnose sleep disorders.
This genotype is less common than the GG and GC genotypes in most studied populations.
Understanding the rs1012477 Variant
The rs1012477 variant is a specific change in the DNA sequence of the PER3 gene. In genetics, a single nucleotide polymorphism (SNP) like rs1012477 represents a variation at a single position in the genome. This particular SNP is located within the PER3 gene, which provides instructions for making a protein that helps regulate the body's sleep-wake cycles. Scientists study these variations to understand how small differences in our genetic code might influence biological processes, such as how our bodies respond to light and dark cycles or how they maintain homeostasis over a 24-hour period. Because this variant is located in a gene critical to the circadian system, it has been a subject of interest in studies examining sleep patterns and related health outcomes.
The Role of the PER3 Gene
The PER3 gene, or Period Circadian Regulator 3, is one of the core clock genes in humans. These genes work together in a complex feedback loop to generate and maintain circadian rhythms, which are the physical, mental, and behavioral changes that follow a 24-hour cycle. The protein produced by PER3 interacts with other clock proteins to inhibit the transcription of certain genes, effectively acting as a molecular timer. By modulating the timing and intensity of sleep, PER3 plays a vital role in our ability to adapt to environmental cues like sunlight. Disruptions or variations in this gene can theoretically impact the precision of this internal clock, potentially influencing sleep quality, diurnal preferences, and the body's overall adaptive responses to external stressors.
Research Associations and Evidence Strength
The evidence linking rs1012477 to specific health outcomes is currently considered limited. Some epidemiological research has suggested a statistical association between this variant and breast cancer risk, particularly among pre-menopausal women and in cases involving ER/PR positive status. However, these findings are based on specific population stratifications and require further validation to be considered conclusive. Other studies on PER3 variants have looked at their role in sleep-wake cycles and depressive symptoms, highlighting the gene's importance in circadian biology. It is important to note that these associations are statistical in nature and do not imply a direct cause-and-effect relationship. Because the evidence is derived from specific, often smaller, study groups, the findings may not be universally applicable across all populations or ancestries.
Interpreting Your Genetic Information
If you have information about your rs1012477 genotype, it is important to view it within the context of current scientific understanding. This variant is a common genetic marker, and its presence does not serve as a diagnostic tool for any medical condition. Genetic associations are complex and are influenced by a wide array of environmental, lifestyle, and other genetic factors. You cannot use this information to predict your personal health outcomes or to make medical decisions. If you have concerns about your sleep patterns, circadian health, or any other medical issues, the most appropriate step is to consult with a qualified healthcare professional. They can provide personalized guidance based on your clinical history and current health status, rather than relying on isolated genetic data.
How common is this variant?
The rs1012477 variant is considered a common polymorphism, with its frequency varying across different ancestral groups as documented in large-scale genomic databases.
Frequently asked questions
Is rs1012477 a diagnostic test for breast cancer?
No, rs1012477 is not a diagnostic test. While some studies have observed statistical associations between this variant and breast cancer risk in specific groups, it is not used in clinical settings to diagnose or predict the disease.
Does this variant mean I have a sleep disorder?
No. Having a specific genotype at this location does not mean you have a sleep disorder. Circadian rhythms are influenced by many factors, and this SNP is only one small piece of a very complex biological system.
Should I change my lifestyle based on this SNP?
You should not make medical or lifestyle changes based solely on this genetic variant. Always consult with a healthcare provider before making significant changes to your health regimen.
Where can I find more information on PER3?
You can find reliable information on the PER3 gene through resources like MedlinePlus Genetics or the NCBI Gene database. These platforms provide comprehensive summaries of gene functions and their roles in human health.
Sources & further reading
Educational information only, last refreshed 10/15/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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This SNP is associated with average delta power during sleep, a marker of sleep intensity.
Common synonymous variant in PER3 tightly linked with circadian diurnal preference and morningness-eveningness tendencies.
Missense variant P415A in PER3 associated with familial advanced sleep phase syndrome and circadian phase preference.
Associated with individual variability in circadian phase and diurnal preference (extreme morningness vs eveningness chronotypes).
Promoter/intronic variant of PER3 tagging circadian phase angle, diurnal preference, and homeostatic sleep pressure response to sleep loss.
This promoter region variant is associated with individual differences in diurnal preference and sleep timing.