CSNK1D rs121913534: Understanding Advanced Sleep Phase Syndrome
The rs121913534 variant is a rare genetic change located within the CSNK1D gene. It has been studied for its potential association with familial advanced sleep phase syndrome, a condition characterized by a shift in the body's internal clock.
What each genotype means
Typical circadian rhythm
This is the most common genotype found in the general population. It is not associated with the rare, inherited sleep patterns linked to this specific variant.
This genotype is found in the vast majority of the population across all ancestries.
Potential circadian rhythm variation
This genotype represents a rare variant that has been identified in families with Familial Advanced Sleep Phase Syndrome (FASPS). Individuals with this genotype may experience a persistent pattern of early evening sleep onset and early morning awakening, though the clinical expression can vary significantly between individuals.
This genotype is extremely rare and is typically only identified in specific families affected by advanced sleep phase conditions.
Rare circadian rhythm variant
This genotype is associated with rare, inherited sleep disorders characterized by an advanced circadian phase. Research indicates that such variants can accelerate the internal body clock, leading to a consistent shift toward earlier sleep and wake times compared to the general population.
This genotype is exceptionally rare in the general population and is primarily documented in clinical research involving families with hereditary sleep phase disorders.
Understanding the CSNK1D Gene
The CSNK1D gene provides instructions for producing an enzyme known as casein kinase 1 delta. This enzyme plays a critical role in regulating the circadian rhythm, which is the internal biological clock that governs the sleep-wake cycle in humans. By phosphorylating various proteins involved in the molecular clock mechanism, this enzyme helps determine the timing of when we feel sleepy and when we feel alert. Because of its central role in maintaining the 24-hour cycle, variations in this gene can potentially disrupt the normal timing of these processes, leading to shifts in sleep patterns.
The Association with Sleep Phase
Research has linked specific variants in the CSNK1D gene to familial advanced sleep phase syndrome (FASPS2). Individuals with this condition typically experience a sleep-wake cycle that is shifted several hours earlier than the conventional schedule, meaning they may feel the urge to sleep very early in the evening and wake up correspondingly early in the morning. While some variants in this gene have been identified in families with this syndrome, the evidence for any single variant, including rs121913534, is often based on small, clinically ascertained family studies. Large-scale population studies, such as those using the UK Biobank, have noted that while these genes are involved in circadian regulation, the effects of rare variants in the general population can be difficult to quantify and may differ from the severe phenotypes observed in specific families.
Population Frequency and Research Context
The rs121913534 variant is considered rare in the general population. Genetic studies often struggle to capture the full impact of such rare variants because they are not common enough to show up frequently in large, diverse cohorts. In some large-scale analyses, researchers have identified very few carriers of specific CSNK1D variants, making it challenging to draw broad conclusions about their prevalence or their exact influence on sleep timing for the average person. Because these variants are often identified through family-based discovery, their presence in the wider population may not always result in the same clinical presentation of advanced sleep phase syndrome.
Interpreting Genetic Information
It is important to understand that having a rare variant does not necessarily mean an individual will develop a specific sleep disorder. Sleep patterns are complex and influenced by a combination of genetic, environmental, and lifestyle factors. If you are concerned about your sleep patterns or believe you may have a circadian rhythm disorder, it is essential to consult with a healthcare professional or a sleep specialist. They can provide a proper clinical evaluation, which is far more informative than looking at a single genetic variant in isolation. Never use genetic information to self-diagnose or make changes to your health regimen without professional medical guidance.
How common is this variant?
The rs121913534 variant is classified as rare, with very low frequency observed across global populations in large-scale genomic databases.
Frequently asked questions
What is familial advanced sleep phase syndrome?
It is a rare condition where a person's internal clock is set to an earlier time than normal. This causes them to fall asleep and wake up much earlier than the typical social schedule.
Does this variant guarantee I have a sleep disorder?
No. Genetic variants are only one piece of the puzzle. Sleep disorders are complex and influenced by many factors, and a clinical diagnosis requires a professional evaluation.
Can I use this information to change my sleep schedule?
You should not use genetic data to make medical decisions. If you are struggling with your sleep, please speak with a doctor or a sleep specialist for personalized advice.
Where can I find more information on CSNK1D?
You can look at resources like the National Institutes of Health's MedlinePlus Genetics or the OMIM database for detailed scientific information on genes and their associated conditions.
Sources & further reading
Educational information only, last refreshed 10/10/2026. Not medical advice — these associations describe population statistics, not individual predictions.
Curious what your genotype is for rs121913534?
Upload a raw DNA file from 23andMe, AncestryDNA, MyHeritage, or FamilyTreeDNA and see this variant — plus thousands more — interpreted in your full report.
Get my report — $29Related variants in CSNK1D
This missense mutation (Thr44Ala) in the CSNK1D gene is a known cause of familial advanced sleep phase syndrome (FASPS) and has been linked to migraine susceptibility.
Variant in casein kinase 1 delta associated with circadian rhythm alterations and subjective disturbed sleep duration.
The T44A missense mutation in CSNK1D accelerates circadian period length and is linked to familial advanced sleep phase syndrome and migraine.
A missense variant (p.Thr44Ala) in CSNK1D that impairs kinase activity and causes familial advanced sleep phase syndrome type 2 (FASPS2).
A rare missense variant (p.His205Arg) in CSNK1D causing familial advanced sleep phase syndrome type 2.
Missense variant (Thr44Ala) in CSNK1D causing familial advanced sleep phase syndrome 2 (FASPS2) with comorbid migraine aura by altering kinase activity on PER proteins.