CLOCK rs3749474: What Your Genotype Means
The rs3749474 variant is a common single-nucleotide polymorphism located within the CLOCK gene. Research suggests this variant is associated with variations in circadian rhythm, metabolic health, and individual responses to dietary weight-loss interventions.
What each genotype means
Baseline metabolic profile
This genotype is often considered the non-risk form in studies examining obesity and metabolic parameters. Research suggests individuals with this genotype may have different associations with dietary intake and body mass index compared to those carrying the T allele. Please note that these associations are statistical observations in populations and do not predict individual health outcomes.
This is a common genotype, though its prevalence varies significantly across global populations.
Increased metabolic risk
Carrying one copy of the T allele has been associated with an increased risk of being overweight or obese in some adolescent and adult studies. Research indicates that carriers may show a positive association between evening carbohydrate intake and body mass index. You should focus on maintaining a balanced diet and consistent sleep schedule, and discuss any specific metabolic concerns with your healthcare provider.
This is a common genotype found in a significant portion of the population, with frequencies varying by ancestry.
Elevated metabolic risk
Individuals with this genotype carry two copies of the minor T allele, which has been linked to higher body mass index and increased waist circumference in various studies. Research suggests that carriers may be more sensitive to the timing and composition of their diet, particularly regarding evening carbohydrate consumption. These findings are based on population-level data; please consult with a clinician or registered dietitian for personalized nutritional guidance.
This genotype is less common than the CC or CT forms, with its frequency varying across different ethnic and geographic groups.
Understanding the rs3749474 Variant
The rs3749474 variant is a specific genetic change located in the 3'-untranslated region (3'-UTR) of the CLOCK gene. In genetics, a single-nucleotide polymorphism (SNP) like rs3749474 represents a variation at a single position in the DNA sequence. Because this variant sits in the 3'-UTR, it is positioned in a region of the gene that does not code for protein directly but is often involved in regulating how much protein is produced or how stable the messenger RNA (mRNA) remains. Scientists study this specific location because variations here may influence the expression levels of the CLOCK protein, which is a fundamental component of the body's internal biological clock. By analyzing this site, researchers aim to understand how subtle differences in our genetic code contribute to the diversity of human sleep patterns and metabolic processes.
The Role of the CLOCK Gene
The CLOCK gene, which stands for Circadian Locomotor Output Cycles Kaput, encodes a transcription factor that acts as a master regulator of the circadian rhythm. This internal clock governs the 24-hour cycle of physiological processes, including sleep-wake cycles, hormone release, and metabolic activity. The CLOCK protein works in a complex feedback loop with other proteins to synchronize cellular functions with the external environment, such as light and dark cycles. Because metabolism is tightly linked to these rhythms, the CLOCK gene is also implicated in energy homeostasis, appetite regulation, and how the body processes nutrients. When the function of this gene is altered, it may lead to desynchrony, where internal biological processes become misaligned with external cues, potentially impacting overall metabolic health and weight regulation.
Research Associations and Evidence
Scientific research has investigated the association between rs3749474 and various health traits, particularly in the context of obesity and metabolic parameters. Some studies have observed that carriers of the T allele may show differences in body mass index (BMI) and waist circumference compared to non-carriers. Furthermore, research into chrononutrition—the study of how the timing of food intake interacts with circadian rhythms—has suggested that this variant might influence weight loss outcomes in individuals participating in structured dietary programs. However, it is important to note that the evidence for these associations is considered moderate. Many studies report that the individual impact of this variant is modest, and results can vary significantly between different populations and study designs. Because these traits are complex and influenced by many genes and environmental factors, the presence of this variant does not determine a specific health outcome.
Population Frequency
The rs3749474 variant is considered a common polymorphism in human populations. Data from genetic studies indicate that both the C and T alleles are present at significant frequencies, making various genotype combinations (CC, CT, and TT) observable in the general population. The distribution of these alleles can vary by ancestry, which is a common feature of many genetic variants. Because it is common, it is frequently included in large-scale genetic association studies to better understand its role in human health.
Interpreting Your Genetic Information
Information about your genotype for rs3749474 is for educational purposes only and should not be used to diagnose or treat any medical condition. While research suggests associations with metabolic traits, these findings are based on statistical trends across large groups of people and cannot predict individual health outcomes. Many factors, including diet, physical activity, sleep hygiene, and other genetic variants, play a much larger role in your overall health than any single SNP. If you are concerned about your weight, metabolic health, or sleep patterns, it is essential to consult with a qualified healthcare provider or a registered dietitian. They can provide personalized guidance based on your clinical history and current health status. Never use genetic information to make changes to your medical care or dietary habits without professional supervision.
How common is this variant?
The rs3749474 variant is a common polymorphism, with the T allele occurring at a significant frequency across diverse populations.
Frequently asked questions
Does having the TT genotype mean I will be obese?
No. Genetic variants like rs3749474 are associated with statistical trends in large populations, not individual outcomes. Obesity is a complex condition influenced by many genetic, environmental, and lifestyle factors.
Can I use this SNP to time my meals for better weight loss?
While some research explores the link between CLOCK variants and chrononutrition, there is no standardized medical advice based on this SNP. You should discuss any significant changes to your diet or meal timing with a registered dietitian or doctor.
Is rs3749474 the same as other CLOCK gene variants?
No, rs3749474 is a specific location in the DNA. Other variants, such as rs1801260, are also studied in the CLOCK gene but represent different genetic changes that may have different associations.
Where can I find more information about my specific genotype?
You can look up your raw genetic data if you have taken a consumer DNA test, but it is best to interpret this information with a genetic counselor. Always prioritize clinical data and professional medical advice over individual SNP results.
Sources & further reading
Educational information only, last refreshed 10/27/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Polymorphism in the CLOCK gene linked to sleep disturbances and metabolic health markers in adolescent populations.
Carriers of the T allele are associated with significantly shorter sleep duration.
Widely studied 3-prime UTR single nucleotide polymorphism (3111T/C) in CLOCK that influences individual evening chronotype, delayed sleep timing, and daytime sleepiness.
A 3-UTR single nucleotide polymorphism in the core CLOCK gene associated with evening chronotype.
3' UTR polymorphism in the core circadian regulator gene associated with evening chronotype ('night owl' tendency) and delayed sleep phase.
CLOCK 3111T/C variant influences circadian timing; associated with eveningness and sleep-schedule preference.