rs1238574 — SULT1E1 SULT1E1 intronic variant

SULT1E1 rs1238574 — Estrogen Clearance, Local Hormone Balance, and Cancer Susceptibility

Estrogens do not simply circulate and act — they are continuously inactivated and reactivated in tissues through a biochemical toggle controlled by sulfotransferases and sulfatases. SULT1E1¹¹ SULT1E1
Estrogen sulfotransferase; a phase II metabolizing enzyme that adds a sulfate group to estradiol and estrone, converting them to biologically inactive sulfate conjugates that cannot bind the estrogen receptor is the primary enzyme responsible for this inactivation step, with particularly high activity in endometrial, hepatic, and placental tissue. When SULT1E1 activity falls — whether through genetic variation, epigenetic silencing, or tissue-specific dysregulation — local estrogen concentrations rise in ways that circulating hormone assays may not capture.

rs1238574 is an intronic variant located deep within SULT1E1 (c.772+856 on the transcript, chr4:69843305 GRCh38). It does not change the SULT1E1 protein sequence, but its position within an intron raises the possibility of effects on pre-mRNA processing, intronic regulatory elements, or splicing efficiency. The C allele — the minor allele globally at roughly 5–6% in European populations but substantially more common in East Asians (~36%) — has been associated with worse cancer outcomes and is the focus of emerging research interest.

The Mechanism

SULT1E1 sulfates estradiol (E2) and estrone (E1) at the 3-hydroxyl position, producing estrogen sulfates that are hydrophilic, receptor-inactive, and destined for excretion. This sulfation reaction is the counterpart to steroid sulfatase (STS), which cleaves the sulfate back off — the balance between SULT1E1 and STS sets local estrogen tone in tissues independently of the ovarian cycle.

Studies of endometriosis tissue directly document this imbalance: SULT1E1 mRNA and protein expression are significantly reduced in ovarian endometriotic lesions²² SULT1E1 mRNA and protein expression are significantly reduced in ovarian endometriotic lesions
Hevir et al. Mol Cell Endocrinol, 2013, creating a state of local estrogen excess driven not by increased synthesis but by impaired inactivation. A 2024 study using Mendelian randomization³³ 2024 study using Mendelian randomization
Zou et al. Biology (Basel), 2024 identified SULT1E1 as a likely causal susceptibility gene for ovarian endometriosis through cross-tissue regulatory network analysis, suggesting genetically determined variation in SULT1E1 expression can propagate into disease risk.

The Evidence

The most direct evidence linking rs1238574 to clinical outcomes comes from a Chinese case-control study of estrogen metabolic pathway genes and colorectal cancer⁴⁴ Chinese case-control study of estrogen metabolic pathway genes and colorectal cancer
Li et al. Archives of Toxicology, 2018. Among SULT1E1 variants studied, rs1238574 was associated with significantly worse progression-free survival (HR = 1.24, 95% CI 1.02–1.50, P = 0.028) and overall survival (HR = 1.51, 95% CI 1.16–1.97, P = 0.002) in colorectal cancer patients. The companion variant rs3822172 showed similar associations (HR = 1.30–1.53). These findings are biologically coherent: estrogens have been proposed to reduce colorectal cancer risk partly through anti-inflammatory and cell-cycle effects, and impaired estrogen inactivation in colonic tissue could paradoxically alter local estrogenic signaling quality.

At the gene level, SULT1E1 variants have been connected to endometrial cancer risk in a population-based case-control study of 502 cases and 1,326 controls⁵⁵ population-based case-control study of 502 cases and 1,326 controls
Rebbeck et al. J Natl Cancer Inst, 2006: the SULT1E1 promoter G→A variant carried an odds ratio of 1.45 (95% CI 1.06–1.99) for endometrial cancer, particularly when combined with hormone replacement therapy use. A separate Korean study⁶⁶ Korean study
Choi et al. Cancer Epidemiol Biomarkers Prev, 2005 found SULT1E1 haplotypes were associated with both breast cancer risk and recurrence (hazard ratio >3 for certain haplotype combinations).

The evidence for rs1238574 specifically is limited to a single study in a Chinese cohort and is classified as emerging. Replication in independent cohorts and functional characterization of this intronic variant's effect on SULT1E1 expression are needed.

Practical Actions

For individuals carrying the C allele, particularly in the context of estrogen-sensitive conditions or cancer risk assessment, the relevant clinical consideration is whether SULT1E1-mediated estrogen inactivation is functioning optimally. Phytoestrogens from soy — specifically isoflavones — have been shown to elevate SULT1E1 enzyme levels in endometriotic stromal cells⁷⁷ elevate SULT1E1 enzyme levels in endometriotic stromal cells
Tarumi et al. Gynecol Endocrinol, 2025, suggesting dietary phytoestrogen intake may partially compensate for reduced SULT1E1 activity. Cruciferous vegetables support phase II metabolism broadly.

Monitoring for estrogen-driven conditions — endometriosis, uterine fibroids, and estrogen-sensitive cancers — is a reasonable precaution for C allele carriers given the biological plausibility of the SULT1E1 pathway and the emerging cancer survival data.

Interactions

rs3822172 (SULT1E1): This second SULT1E1 intronic variant was studied in the same Chinese colorectal cancer cohort as rs1238574 and showed nearly identical survival associations (HR = 1.30 for PFS, HR = 1.53 for OS). Whether these two variants are in linkage disequilibrium or tag independent functional effects within SULT1E1 is not yet established. Both should be considered together when assessing SULT1E1 function.

Estrogen metabolism pathway: SULT1E1 operates in concert with CYP1B1 (which activates catechol estrogens), CYP1A1 (estrogen hydroxylation), STS (sulfatase reactivation), and UGT enzymes (glucuronidation). Combined variation across these enzymes, particularly CYP1A1 and SULT1A1, has been associated with amplified endometrial cancer risk in case-control studies. Compound action proposals for supervisor: consider a SULT1E1/CYP1A1 interaction action if rs1238574 and a CYP1A1 risk allele co-occur in the same user, given the documented combined OR of 4.58 (Hirata et al. 2008, PMID 18318428).