SMAD7 rs4464148: Understanding Colorectal Cancer Risk Associations
The genetic variant rs4464148 is a single nucleotide polymorphism (SNP) located within the SMAD7 gene. Research has identified this variant as being associated with a modest increase in the risk of developing colorectal cancer.
What each genotype means
Baseline colorectal cancer risk
This genotype is considered the reference or baseline state for this variant in the SMAD7 gene. Research indicates that individuals with this genotype do not carry the specific risk-associated allele linked to increased colorectal cancer susceptibility in this study context.
This is the most common genotype observed in many populations, though exact frequencies vary by ancestry.
Slightly increased cancer risk
Carrying one copy of the C allele is associated with a modest increase in the statistical risk of developing colorectal cancer compared to those with the TT genotype. Some studies suggest this association may be more pronounced in women, though findings have been mixed across different research cohorts.
This heterozygous genotype is found in a significant portion of the population, with frequencies varying across different ethnic groups.
Elevated colorectal cancer risk
Individuals with this genotype carry two copies of the C allele, which has been statistically associated with a higher risk of colorectal cancer compared to the TT and CT genotypes. While this association is documented in large-scale studies, it represents a modest predisposition rather than a diagnosis, and individuals should focus on standard screening guidelines.
This homozygous genotype is less common than the heterozygous form, with prevalence varying significantly by ancestral background.
What is rs4464148?
A single nucleotide polymorphism, or SNP, is a variation at a single position in a DNA sequence among individuals. The variant rs4464148 is located on chromosome 18 within the SMAD7 gene. In the context of this SNP, the two possible nucleotides at this specific location are cytosine (C) and thymine (T). Because humans carry two copies of every chromosome, individuals can have one of three possible genotypes: TT, CT, or CC. Scientists study these variations to understand how specific changes in the genetic code might influence biological processes or susceptibility to certain health conditions. By comparing the frequency of these genotypes in large groups of people with and without a specific disease, researchers can identify statistical links between the variant and the condition.
The Role of the SMAD7 Gene
The SMAD7 gene provides instructions for making a protein that acts as a negative regulator of the TGF-beta signaling pathway. This pathway is essential for controlling cell growth, differentiation, and apoptosis, which is the process of programmed cell death. When the TGF-beta pathway is functioning correctly, it helps prevent cells from growing uncontrollably. SMAD7 works by inhibiting the signals that would otherwise promote cell proliferation. Because of its role in maintaining cellular balance, variations in the SMAD7 gene are of interest to cancer researchers. If the regulation of this pathway is disrupted, it may contribute to the development or progression of tumors. Understanding how variants like rs4464148 might influence the expression or function of the SMAD7 protein is an active area of ongoing scientific investigation.
Research and Evidence Strength
The association between rs4464148 and colorectal cancer has been identified through genome-wide association studies (GWAS). These studies analyze the entire genome to find markers that appear more frequently in people with a disease compared to those without it. Evidence for this specific variant is considered moderate. Some studies have reported that individuals carrying the C allele show a higher statistical risk for colorectal cancer compared to those with the T allele. However, the strength of this association can vary between studies, and some research has suggested that the effect might be more pronounced in specific subgroups, such as women. It is important to note that these findings represent statistical correlations across large populations rather than a direct cause-and-effect relationship for any single individual. Genetic risk is complex and typically involves the interplay of many different genes and environmental factors.
Population Frequency
The frequency of the C and T alleles for rs4464148 varies across different global populations. According to data from large-scale genomic projects, the minor allele frequency (MAF) is approximately 0.21, though this can fluctuate depending on the ancestral background of the group being studied. Because this is a common variant, a significant portion of the general population carries at least one copy of the C allele. Understanding these frequencies helps researchers determine if a variant is common enough to contribute to disease risk at a population level. While these statistics provide context for how widespread the variant is, they do not predict the health outcome for any specific person.
Interpreting Your Genetic Information
If you have access to your genetic data and find that you carry the rs4464148 variant, it is important to maintain perspective. This SNP is only one of many factors that contribute to colorectal cancer risk. Most people who carry the C allele will never develop the disease, and many who do not carry it may still be at risk due to other genetic, lifestyle, or environmental factors. This information is not a medical diagnosis and cannot predict your personal health future. If you are concerned about your risk for colorectal cancer, the most effective steps involve discussing your family history and screening options with a healthcare professional. They can provide personalized guidance based on established clinical guidelines, which are far more predictive than any single genetic variant.
How common is this variant?
The minor allele (C) has a frequency of approximately 0.21, making it a relatively common variant across many global populations.
Frequently asked questions
Does having the CC genotype mean I will get cancer?
No. This variant is associated with a statistical increase in risk across large populations, but it is not a diagnostic test. Most people with the CC genotype will not develop colorectal cancer.
Should I get screened for cancer if I have this variant?
You should follow standard medical guidelines for colorectal cancer screening regardless of your genetic results. Always discuss your family history and personal risk factors with your doctor to determine the appropriate screening schedule.
Can I change my risk associated with rs4464148?
While you cannot change your genetics, you can manage your overall risk through lifestyle choices such as a healthy diet, regular exercise, and avoiding tobacco. Consult a healthcare provider for evidence-based strategies to reduce your cancer risk.
Where can I find more information about this SNP?
You can look up rs4464148 in databases like the GWAS Catalog or NCBI's dbSNP. These resources provide technical details and links to the original scientific studies that identified the association.
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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This variant is significantly associated with colorectal cancer recurrence in patients with stage II disease.
This variant is significantly associated with colorectal cancer recurrence in patients with stage III disease.
This variant is located in a low-complexity region and has been identified in recent genomic catalogs as a rare variant of interest.