What you carry at this position in your DNA and what research says about it.
Cancer Susceptibility Risk: 10/10 evidence, 37 publications.
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Sample genotype (not yours): A/A
Higher Risk of Colorectal and Prostate Cancers
Two copies of the A allele are associated with the highest risk of developing colorectal and prostate cancers. This genetic profile is also linked to a higher likelihood of developing colon polyps.
What this genotype means: Increased risk of colorectal cancer; Increased risk of early-onset prostate cancer; Higher likelihood of colon polyps.
Sample genotype (not yours): A/G
Moderately Increased Risk of Colorectal and Prostate Cancers
One copy of the A allele is associated with a moderately increased risk of colorectal and prostate cancers. This profile also slightly elevates the likelihood of developing colon polyps.
What this genotype means: Moderately increased risk of colorectal cancer; Moderately increased risk of prostate cancer; Slightly higher likelihood of colon polyps.
Sample genotype (not yours): G/G
Typical Colorectal Cancer Risk
Two copies of the G allele are associated with a typical baseline risk of colorectal cancer. This genetic setup represents the most common profile at this locus.
What this genotype means: Typical baseline risk of colorectal cancer; Typical baseline risk of prostate cancer; No elevated risk of colon polyps.
Gene function and biological role
Gene Function: CASC8 (cancer susceptibility 8) is a long non-coding RNA gene located on chromosome 8q24, a region heavily implicated in multiple cancers [1]. Although it does not encode a protein, CASC8 plays a crucial regulatory role in cell proliferation and tumor progression [2]. It is thought to interact with chromatin-modifying complexes and transcription factors to influence the expression of nearby oncogenes [2]. Dysregulation of CASC8 has been observed in colorectal, prostate, and gastric cancers [2].
Variant Impact: The rs10505477 variant is an intronic single nucleotide polymorphism located within the CASC8 gene [1]. This genetic change alters the regulatory landscape of the 8q24 region, which is often referred to as a cancer desert due to its lack of protein-coding genes but abundance of disease-associated variants [1]. The alteration is thought to affect the expression of CASC8 and neighboring genes like POU5F1B, which are involved in cell stemness and growth [3]. Carrying the A allele at this locus is consistently associated with an increased susceptibility to several hormone-sensitive and gastrointestinal cancers [1] [4].
Key Insight: This variant lies in a gene desert on chromosome 8, meaning it does not code for a protein but acts as a powerful genetic switch regulating nearby cancer-related genes.
Location: CASC8. Chromosome 8 · 8q24.21 · 127.4 Mb
Estimated prevalence by population
Global 37.1%; European 24.9%; African 68.6%; East Asian 15.9%; South Asian 23.5%; Americas 29.0%; Ashkenazi 25.0%; Finnish 24.9%; Middle Eastern 28.9%; Amish 40.2%.
Estimated AA genotype frequency.
Global 43.9%; European 50.0%; African 28.4%; East Asian 47.9%; South Asian 50.0%; Americas 49.7%; Ashkenazi 50.0%; Finnish 50.0%; Middle Eastern 49.7%; Amish 46.4%.
Estimated AG genotype frequency.
Global 19.0%; European 25.2%; African 2.9%; East Asian 36.2%; South Asian 26.6%; Americas 21.3%; Ashkenazi 25.0%; Finnish 25.1%; Middle Eastern 21.4%; Amish 13.4%.
Estimated GG genotype frequency.
Showing effects for A/A genotype
Cancer & Oncology
Colorectal Cancer
Colorectal Cancer. Evidence: 8/10. Source: PMID 17618283. ~1.17x Higher Risk.
Colon Polyps. Evidence: 8/10. Source: PMID 39024449. Increased Risk.
Prostate Cancer
Prostate Cancer. Evidence: 10/10. Source: PMID 24740154. ~1.39x Higher Risk.
PSA Levels. Evidence: 6/10. Source: PMID 28139693. Slightly Higher.
Showing effects for A/G genotype
Colorectal Cancer. Evidence: 8/10. Source: PMID 17618283. Slightly Higher Risk.
Colon Polyps. Evidence: 8/10. Source: PMID 39024449. Slightly Higher Risk.
Prostate Cancer. Evidence: 10/10. Source: PMID 24740154. Slightly Higher Risk.
PSA Levels. Evidence: 6/10. Source: PMID 28139693. Typical.
Showing effects for G/G genotype
Colorectal Cancer. Evidence: 8/10. Source: PMID 17618283. Typical Risk.
Colon Polyps. Evidence: 8/10. Source: PMID 39024449. Typical Risk.
Prostate Cancer. Evidence: 10/10. Source: PMID 24740154. Typical Risk.
What this genotype means for the people who carry it
Sample genotype: AA (Homozygous)
Inheriting two copies of the A allele is associated with a significantly increased risk of colorectal cancer, with studies showing an odds ratio of approximately 1.17 compared to non-carriers [1]. Research also indicates a stronger association with early-onset prostate cancer, elevating the risk by nearly 1.4 times [2]. The genetic variation at this locus is believed to influence the expression of nearby genes involved in cell growth and tumor development [1]. In addition to cancer risk, individuals with this genotype are more likely to develop benign colon polyps, which can sometimes serve as precursors to colorectal tumors [3]. Furthermore, this variant is associated with slightly elevated baseline levels of prostate-specific antigen (PSA), an important biomarker used in prostate screening [4].
Increased risk of colorectal cancer; Increased risk of early-onset prostate cancer; Higher likelihood of colon polyps.
Sample genotype: AG (Heterozygous)
A single copy of the risk-associated A allele confers a moderately elevated susceptibility to colorectal cancer compared to those with two protective copies [1]. It is also linked to an increased risk of early-onset prostate cancer, though to a lesser degree than carrying two copies of the risk allele [2]. The variant is located in a regulatory region on chromosome 8q24 that influences cell proliferation pathways [1]. Individuals with this genotype may also have a slightly higher chance of developing colon polyps [3]. Baseline prostate-specific antigen (PSA) levels may also be slightly higher, which is a common marker monitored for prostate health [4].
Moderately increased risk of colorectal cancer; Moderately increased risk of prostate cancer; Slightly higher likelihood of colon polyps.
Sample genotype: GG (Homozygous)
Two copies of the G allele represent the protective or typical baseline profile because this combination lacks the risk-associated A allele. Individuals with this genotype have a lower, typical risk of developing colorectal cancer compared to carriers of the A allele [1]. Similarly, the risk of early-onset prostate cancer remains at the standard population baseline [2]. Because this genotype does not alter the regulatory activity of the CASC8 gene region, cell growth pathways function normally without this specific inherited risk factor [1]. The likelihood of developing colon polyps is also not elevated by this variant [3]. Baseline prostate-specific antigen (PSA) levels are typically lower and more stable compared to those carrying the risk allele, which can help prevent false-positive signals during routine prostate screenings [4].
Typical baseline risk of colorectal cancer; Typical baseline risk of prostate cancer; No elevated risk of colon polyps.
Variants with shared genetic architecture
rs13281615 · CASC8 Gene · Chr 8 · Breast Cancer Risk
rs1447295 · CASC8 Gene · Chr 8 · Prostate Cancer Risk
rs6983267 · CASC8 Gene · Chr 8 · Cancer Risk
Genome-wide association scan identifies a colorectal cancer susceptibility locus on chromosome 8q24.
Pan-cancer study detects genetic risk variants and shared genetic basis in two large cohorts.
Genome-wide association scan for variants associated with early-onset prostate cancer.
Content updated August 2026.
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