rs1457043 — CYP7A1

Intronic variant in CYP7A1 that tags a haplotype block influencing cholesterol 7α-hydroxylase expression; CC homozygotes show elevated LDL-cholesterol and increased subclinical atherosclerosis risk across multiple population studies

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CYP7A1 — The Cholesterol Elimination Gateway

CYP7A111 CYP7A1
Cytochrome P450 family 7, subfamily A, member 1 — encodes cholesterol 7α-hydroxylase, the rate-limiting enzyme converting cholesterol to bile acids in the liver controls the single most important route by which the body permanently removes cholesterol. Every day, cholesterol 7α-hydroxylase converts a portion of your liver's cholesterol pool into primary bile acids — cholic acid and chenodeoxycholic acid — which are secreted into the gut, aid fat digestion, and are partially excreted in feces. The rate of this reaction sets how efficiently your body can clear excess cholesterol from circulation.

The rs1457043 variant is an intronic C-to-T substitution at position 58,497,880 on chromosome 8 (GRCh38), within the CYP7A1 gene on the minus strand. It does not change the CYP7A1 protein sequence but sits within a haplotype block that includes functionally important promoter and enhancer variants. Multiple population studies have identified rs1457043 as a tag SNP that co-segregates with CYP7A1 expression differences and associated lipid phenotypes.

The Mechanism

As an intron variant22 intron variant
a DNA change within a non-coding intervening sequence; can affect splicing, mRNA stability, local chromatin structure, or expression through regulatory elements without altering the protein sequence directly, rs1457043 does not directly alter CYP7A1 enzyme function. Its clinical relevance derives from linkage disequilibrium33 linkage disequilibrium
the non-random association of alleles at two loci; nearby variants tend to be inherited together on the same chromosomal segment, so a tag SNP can predict the state of nearby functional variants with functional CYP7A1 regulatory variants in the same haplotype block.

The most functionally important variants in this region are rs3808607 (a promoter SNP, -203A>C) and rs9297994 (a downstream enhancer SNP), which together produce more than 100-fold variation in hepatic CYP7A1 mRNA expression44 more than 100-fold variation in hepatic CYP7A1 mRNA expression
Li et al. showed these two SNPs interact through long-range chromatin contacts — their combined genotype, not either alone, predicts CYP7A1 expression, LDL levels, and statin response. rs1457043 recombines more frequently with these promoter variants than do other CYP7A1 SNPs, suggesting it tags a partially independent segment of the haplotype structure. When CYP7A1 activity is reduced, less cholesterol is converted to bile acids, leading to cholesterol accumulation in the liver, compensatory LDL receptor downregulation, and elevated circulating LDL-cholesterol.

The T allele (plus strand) is the major allele globally (~57%) and predominates in European (~59%) and Latino (~70%) populations. The C allele (GRCh38 reference) is in the minority globally but is common in African (~57%) and East Asian (~57%) populations. CC homozygotes — those with two C alleles — show the highest association with adverse lipid profiles in studied populations.

The Evidence

Subclinical atherosclerosis and LDL-cholesterol: The most specific evidence comes from a case-control study in Mexico55 a case-control study in Mexico
Vargas-Alarcón et al. CYP7A1 gene polymorphisms are associated with increased LDL-cholesterol levels and the incidence of subclinical atherosclerosis. Biomol Biomed, 2025 comparing 416 patients with subclinical atherosclerosis (coronary artery calcium > 0) against 1,046 controls. Seven CYP7A1 polymorphisms were analyzed; rs1457043 homozygous minor allele carriers showed elevated incidence of subclinical atherosclerosis and higher LDL-cholesterol levels compared with other genotypes (p < 0.05). The LD analysis additionally showed that rs1457043 recombines more frequently than neighboring SNPs, indicating it partially captures independent haplotype variation.

Acute coronary syndrome and dyslipidemia: A companion study by the same group examined 1,317 ACS patients and 1,046 controls66 examined 1,317 ACS patients and 1,046 controls
Vargas-Alarcón et al. Associations of CYP7A1 gene polymorphisms with risk of acute coronary syndrome, plasma cholesterol, and incidence of diabetes. Biomedicines, 2024 in a Mexican population. While five neighboring variants (rs9297994, rs10504255, rs8192870, rs2081687, rs10107182) reached significance for ACS risk and dyslipidemia, rs1457043 was included in the analysis as part of the broader CYP7A1 haplotype survey.

Drug-induced hepatotoxicity: In Chinese patients receiving anti-tuberculosis medications, rs1457043 CT (plus-strand) heterozygotes77 rs1457043 CT (plus-strand) heterozygotes
Chen et al. CYP7A1, BAAT and UGT1A1 polymorphisms and susceptibility to anti-tuberculosis drug-induced hepatotoxicity. Int J Tuberc Lung Dis, 2016 had OR 2.05 (95% CI 1.18–3.15, p=0.014) for hepatotoxicity compared with CC homozygotes. This finding, combined with haplotype G-C or G-A combinations showing OR 2.40 (95% CI 1.62–3.57), suggests that CYP7A1 haplotype variation modifies hepatic bile acid flux in ways that can amplify drug toxicity. This is distinct from the lipid phenotype and likely reflects CYP7A1's role in liver bile acid homeostasis during pharmacological challenge.

CYP7A1 expression and statin response context: Research on nearby functional variants demonstrates that long-range chromatin interactions between rs3808607 and rs929799488 long-range chromatin interactions between rs3808607 and rs9297994
Li et al. Interactions Between Regulatory Variants in CYP7A1 Promoter and Enhancer Regions Regulate CYP7A1 Expression. Circ Genom Precis Med, 2018 produce the largest known range of CYP7A1 expression variation — over 100-fold. These expression differences correlate with LDL levels, coronary artery disease risk, and statin response, establishing the biological plausibility of rs1457043's haplotype-tagged effects.

Practical Actions

For CC homozygotes, the evidence suggests reduced efficiency of cholesterol-to-bile-acid conversion. The most direct interventions either support bile acid synthesis (plant sterols, soluble fiber) or monitor the downstream LDL consequences. Statins — which indirectly upregulate CYP7A1 expression through cholesterol depletion and SREBP signaling — remain the most evidence-based intervention for elevated LDL; however, the CYP7A1 haplotype context (via linked variants) may affect statin response magnitude and warrants LDL monitoring.

Plant sterols and stanols (2–3 g/day) compete with cholesterol for intestinal absorption, reducing the cholesterol pool that CYP7A1 must handle and independently lowering LDL by 5–15%. Soluble fiber (psyllium, oat beta-glucan) binds bile acids in the gut, reducing enterohepatic recirculation and compelling the liver to synthesize more bile acids from cholesterol — effectively compensating for reduced CYP7A1 activity.

Interactions

rs1457043 is in the same haplotype block as rs3808607 (the CYP7A1 promoter SNP, also called -203A>C or -204A>C in older literature), rs8192870, rs9297994 (downstream enhancer), and rs3824260. Because these variants partially recombine from each other, the combination matters: individuals carrying rs1457043 CC alongside risk haplotypes at rs3808607 and rs9297994 are likely to have the most severely reduced CYP7A1 expression. Conversely, individuals with rs1457043 CC but protective haplotypes at the functional promoter/enhancer SNPs may have attenuated phenotypic consequences. Compound actions across this haplotype block would require genotype data from the functional variants (rs3808607 and rs9297994) as well.

Nutrient Interactions

dietary cholesterol altered_metabolism
soluble fiber altered_metabolism

Genotype Interpretations

What each possible genotype means for this variant.

TT Common Haplotype Normal

Common genotype — standard CYP7A1 bile acid synthesis capacity

The TT genotype represents two copies of the globally common T allele, which is particularly prevalent in European and Latino populations. In the Mexican case-control studies examining CYP7A1 haplotypes and lipid phenotypes, TT homozygotes did not show the elevated LDL-cholesterol or subclinical atherosclerosis associations seen in CC homozygotes. Your cholesterol conversion through the classic bile acid synthesis pathway at this locus functions at the population-normal rate. Other CYP7A1 variants in your profile (rs3808607, rs9297994) are stronger functional determinants of CYP7A1 expression and may further refine this picture.

CT Heterozygote Intermediate

One C allele — intermediate CYP7A1 haplotype; modestly elevated hepatotoxicity risk with certain medications

The CT genotype is the most common genotype globally (~49%). The primary specific evidence for CT involves hepatic bile acid handling during anti-tuberculosis treatment: Chen et al. (2016, PMID 27155186) found CT heterozygotes had roughly twice the risk of drug-induced hepatotoxicity compared with CC homozygotes (OR 2.05, p=0.014), in a case-control study of 89 cases and 356 controls. This counterintuitive finding (CT having higher hepatotoxicity risk than CC) likely reflects haplotype complexity — the CC genotype in that Chinese population co-segregates with protective combinations at nearby functional SNPs. For lipid phenotypes, heterozygotes are not separately characterized in the available studies, which focused on homozygous minor allele carriers. Your overall LDL risk at this locus is intermediate and should be assessed alongside your rs3808607 and rs9297994 status for a complete CYP7A1 haplotype picture.

CC Risk Homozygote High Risk

Two C alleles — elevated LDL-cholesterol and subclinical atherosclerosis risk linked to CYP7A1 haplotype

The CC genotype represents homozygosity for the C allele at this intronic CYP7A1 tag variant. As a tag SNP in linkage disequilibrium with functional promoter and enhancer variants, CC homozygosity predicts a specific CYP7A1 regulatory haplotype associated with reduced or dysregulated CYP7A1 expression. The primary evidence comes from Vargas-Alarcón et al. (2025, PMID 39207177), who found that homozygous minor allele carriers at rs1457043 had elevated LDL-cholesterol levels and significantly higher coronary artery calcium scores (a marker of subclinical atherosclerosis), with p < 0.05 across 416 cases and 1,046 controls. The companion ACS study (PMID 38540230) included this SNP in a seven-variant panel — though five other SNPs drove the primary ACS associations, the broader haplotype context implicates altered CYP7A1-mediated cholesterol clearance.

Mechanistically, when CYP7A1 activity is reduced, the liver converts less cholesterol to bile acids, the hepatic free cholesterol pool rises, SREBP-2 processing is suppressed, LDL receptor expression falls, and LDL clearance from blood decreases. The net result is chronically elevated LDL — a major modifiable risk factor for atherosclerosis. This pathway is distinct from LDL receptor mutations (as in familial hypercholesterolemia) but converges on the same phenotype.

The CC haplotype's clinical significance is likely modulated by your status at the functional promoter SNPs rs3808607 and rs9297994, which together produce the largest expression variation in the CYP7A1 gene. CC at rs1457043 alone captures part of the risk picture; the complete haplotype provides higher resolution.