CSNK1D rs121912441: Understanding the Thr44Ala Variant
The rs121912441 variant is a rare genetic change in the CSNK1D gene that results in a Thr44Ala amino acid substitution. This specific mutation has been identified in research as a cause of familial advanced sleep phase syndrome (FASPS) and is associated with migraine susceptibility.
What each genotype means
Typical circadian timing
You carry two copies of the common standard allele in the CSNK1D gene. This genotype is associated with normal casein kinase 1 delta enzymatic activity and standard circadian sleep-wake rhythm regulation. It is not linked to familial advanced sleep phase syndrome or inherited migraine predisposition associated with this variant.
Carried by virtually 100% of individuals across all major global ancestry populations in gnomAD and dbSNP reference data.
Advanced sleep phase predisposition
You carry one copy of the rare missense variant resulting in the Thr44Ala substitution in the CSNK1D gene. In published familial studies, carrying one copy has been linked to autosomal dominant familial advanced sleep phase syndrome (an extreme 'morning lark' schedule with sleep and wake times shifted significantly earlier) and migraine susceptibility. However, evidence remains limited to small family studies, and individual expression of these traits can vary.
Extremely rare worldwide, identified in isolated pedigree families and virtually absent (frequency <0.0001) in general population databases.
What is the rs121912441 Variant?
The rs121912441 variant is a specific change in the DNA sequence of the CSNK1D gene, often referred to in scientific literature as the Thr44Ala (or T44A) mutation. This is a missense mutation, meaning that a single nucleotide change leads to the substitution of one amino acid for another—in this case, threonine is replaced by alanine at position 44 of the protein. This variant is located on chromosome 17. Because it alters the structure of the resulting protein, researchers have studied it extensively to understand how it impacts biological functions, particularly those related to the body's internal clock and neurological health.
The Role of the CSNK1D Gene
The CSNK1D gene provides instructions for making an enzyme called casein kinase 1 delta (CK1δ). This enzyme is a serine/threonine protein kinase, which acts as a molecular switch by adding phosphate groups to other proteins, a process known as phosphorylation. CK1δ is essential for regulating several critical biological processes, including the circadian rhythm, which governs our sleep-wake cycles. It also plays a role in Wnt signaling, DNA damage repair, and cell cycle control. Because it is so deeply involved in the timing of cellular events, changes to the CSNK1D gene can have significant downstream effects on how the body maintains its daily rhythms and responds to external stimuli.
Research and Clinical Associations
Scientific research has established a strong link between the Thr44Ala mutation and familial advanced sleep phase syndrome type 2 (FASPS2). Individuals with this condition experience a sleep cycle that is shifted several hours earlier than the general population, often causing them to fall asleep and wake up much earlier than desired. Beyond sleep disorders, some studies have suggested that this variant may also contribute to migraine susceptibility. The mechanism is thought to involve reduced kinase activity of the CK1δ enzyme, which disrupts normal neuronal excitability and temporal regulation. While the evidence for its role in FASPS2 is well-documented in clinical studies, the association with migraines is an area of ongoing investigation, reflecting the complex nature of how this gene influences neurological health.
Population Frequency and Interpretation
The rs121912441 variant is considered rare in the general population, with an allele frequency typically reported as less than 0.01%. Because it is so uncommon, it is not a variant that most people will encounter in standard genetic screening. It is important to remember that genetic associations are statistical in nature and do not guarantee the development of a specific condition. If you have questions about your own genetic data or concerns regarding sleep or neurological symptoms, it is essential to discuss these findings with a qualified healthcare provider or a genetic counselor. They can provide context based on your personal health history and help you understand what, if any, clinical steps are appropriate for your situation.
How common is this variant?
The rs121912441 variant is rare, with an allele frequency reported at less than 0.01% in the general population.
Frequently asked questions
What is familial advanced sleep phase syndrome?
FASPS is a rare sleep disorder where an individual's internal clock is set to an earlier time than normal. People with this condition typically fall asleep in the early evening and wake up very early in the morning.
Does having this variant mean I will have migraines?
Not necessarily. While some research links this variant to migraine susceptibility, genetic variants are only one factor in complex conditions. Many people with or without this variant may or may not experience migraines.
Can I change my CSNK1D gene?
No, your genetic sequence is inherited and cannot be changed. However, understanding your genetic predispositions can help you and your doctor manage your health more effectively.
Should I be tested for this variant?
Genetic testing is typically reserved for individuals with specific clinical symptoms or a strong family history of a condition. You should consult with a doctor or genetic counselor to determine if testing is appropriate for you.
Sources & further reading
Educational information only, last refreshed 10/7/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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The T44A missense mutation in CSNK1D accelerates circadian period length and is linked to familial advanced sleep phase syndrome and migraine.
A rare missense variant (p.His205Arg) in CSNK1D causing familial advanced sleep phase syndrome type 2.
Missense variant (Thr44Ala) in CSNK1D; pathogenic for Familial Advanced Sleep Phase Syndrome 2 (FASPS2).
Exonic variant in CSNK1D; while some variants are linked to advanced sleep-wake phase syndrome, population-wide penetrance is often low.
This variant in CSNK1D is linked to familial advanced sleep phase syndrome, influencing circadian period length.
This variant is linked to advanced sleep phase syndrome, affecting the regulation of the circadian clock.