rs11931074 — SNCA

SNCA rs11931074 — The 3′ UTR Variant That Amplifies Alpha-Synuclein and Parkinson's Risk

The SNCA gene¹¹ SNCA gene
Alpha-synuclein (SNCA) encodes the protein that forms the pathological hallmark of Parkinson's disease — Lewy bodies and Lewy neurites — in dopaminergic neurons of the substantia nigra harbours multiple independent risk variants spread across its genomic structure. rs11931074 sits in the 3′ downstream region of SNCA — within or adjacent to an extended 3′ untranslated region (3′ UTR) that recent research has shown stretches much further than previously appreciated. This position gives the variant direct access to the regulatory machinery that controls SNCA mRNA stability, translation efficiency, and ultimately how much alpha-synuclein protein a cell produces.

rs11931074 has been studied across more published meta-analyses than virtually any other common SNCA variant and emerges in the most recent 2025 systematic review as the single most robust SNCA risk marker — showing consistent, low-heterogeneity associations with Parkinson's disease across all tested genetic models and in both Asian and European populations. Its independence from the 3′-block variant rs356219 (which operates through a different regulatory mechanism in a partially overlapping region) makes it an additive source of risk information at the SNCA locus.

The Mechanism

rs11931074 is located at GRCh38 chromosome 4 position 89,718,364, approximately 5–6 kb downstream of the canonical SNCA gene boundary on the plus strand — placing it within an extended 3′ UTR²² extended 3′ UTR
A 2018 study identified alpha-synuclein transcripts in postmortem human brain samples with a 3′ UTR approximately 1,246 nucleotides longer than the canonical form; rs11931074 falls within this extended region that encompasses risk-associated variants previously considered merely downstream of the gene.

The T risk allele at this position is predicted to alter mRNA stability and translation efficiency³³ mRNA stability and translation efficiency
The 3′ UTR is a key regulatory hub: RNA-binding proteins including ELAVL1 and TIAR bind the SNCA 3′ UTR and modulate both mRNA stabilization and translational activation; variants that disrupt these binding sites shift the equilibrium between degradation and active translation in a direction that increases steady-state SNCA expression. Consistent with this, the TT genotype has been directly associated with significantly higher alpha-synuclein protein levels in human brain tissue — providing functional confirmation of the predicted mechanism.

The downstream consequence mirrors the rs356219 story: chronically elevated alpha-synuclein increases the probability of misfolding, oligomerization, and seeding of the insoluble fibrillar aggregates that destroy dopaminergic neurons in the substantia nigra and trigger the progressive motor and non-motor symptoms of Parkinson's disease.

The Evidence

The largest meta-analysis⁴⁴ The largest meta-analysis
Liu et al. An updated analysis with 45,078 subjects confirms the association between SNCA rs11931074 and Parkinson's disease. Neurological Sciences, 2018 pooled 33 studies involving 15,368 PD patients and 29,710 controls. Every tested genetic model reached significance: allelic OR 1.36 (95% CI 1.31–1.42); heterozygous OR 1.44 (95% CI 1.35–1.55); homozygous TT vs. GG OR 1.87 (95% CI 1.68–2.09); recessive OR 1.58 (95% CI 1.46–1.72). Crucially, significant associations appeared in both Asian and Caucasian subgroups, confirming that the risk signal is not ethnicity-specific.

A 2020 meta-analysis⁵⁵ A 2020 meta-analysis
Du et al. Association between alpha-synuclein (SNCA) rs11931074 variability and susceptibility to Parkinson's disease: an updated meta-analysis of 41,811 patients. Neurological Sciences, 2020 (13,403 cases, 28,408 controls) confirmed these results with allelic OR 1.28 (95% CI 1.12–1.45; p=0.0001) and recessive OR 1.40 (95% CI 1.18–1.68; p=0.0002). The study specifically noted low heterogeneity across studies and no evidence of publication bias — two hallmarks of a genuine, reproducible association rather than an artefact of selective reporting.

The 2025 systematic review and meta-analysis⁶⁶ The 2025 systematic review and meta-analysis
Mohammadi et al. Common SNCA Genetic Variants and Parkinson's Disease Risk. International Journal of Molecular Sciences, 2025 including 27 studies explicitly identified rs11931074 as showing "consistent associations with PD across all models" and confirmed it as the most robust common SNCA PD risk variant — more consistent than rs356219, which showed greater heterogeneity across geographic regions.

Beyond disease susceptibility, rs11931074 shows associations with PD clinical features. A 2015 Chinese cohort study⁷⁷ A 2015 Chinese cohort study
Chen et al. Hyposmia correlates with SNCA variant and non-motor symptoms in Chinese patients with Parkinson's disease. Parkinsonism & Related Disorders, 2015 (218 PD patients) found the TT genotype conferred OR 3.24 (95% CI 1.23–8.51) for hyposmia — reduced sense of smell — a well-recognized early non-motor marker of PD. The same study confirmed TT genotype was associated with significantly higher alpha-synuclein levels in brain tissue (p=0.0082), providing the mechanistic link between genotype and phenotype.

A 2019 resting-state fMRI study⁸⁸ 2019 resting-state fMRI study
SNCA rs11931074 polymorphism correlates with spontaneous brain activity and motor symptoms in Chinese patients with Parkinson's disease. Journal of Neural Transmission, 2019 found that TT carriers showed altered spontaneous brain activity in the right angular gyrus compared to GT/GG carriers, with ALFF values negatively correlated with UPDRS III motor scores — suggesting the variant modulates the neural circuitry underlying motor control in affected patients.

Practical Actions

The functional consequence of rs11931074 T-allele carriage — higher alpha-synuclein expression — is the same biological target as for rs356219, meaning the protective strategies that address elevated SNCA expression apply here too: supporting mitochondrial function against alpha-synuclein-driven complex I dysfunction, promoting autophagy to clear misfolded protein, and reducing environmental exposures that independently upregulate SNCA.

The clinically important addition from rs11931074 research is the hyposmia connection. Loss of smell is one of the earliest detectable markers of Parkinson's pathology, appearing years before motor symptoms. TT carriers who notice a declining sense of smell should discuss this with their doctor as a potential early indicator warranting neurological evaluation — the combination of genotype and symptom substantially elevates clinical concern.

Because T allele frequency differs dramatically between populations (about 7% in Europeans versus 53% in East Asians), the genotype interpretation varies substantially by ancestry: TT homozygosity is rare in Europeans (about 1%) but relatively common in East Asians (about 28%), meaning the recessive risk signal has very different population-level impact.

Interactions

rs11931074 and rs356219 are both located in the 3′ region of the SNCA locus but are in different linkage disequilibrium blocks and likely act through partially distinct regulatory mechanisms — rs356219 primarily by altering SNCA transcription, rs11931074 by affecting mRNA stability/translation in the extended 3′ UTR. Independent carriage of risk alleles at both loci may compound alpha-synuclein overproduction through additive regulatory effects, though no single study has formally quantified the joint genotype effect.

rs356182, an intronic SNCA variant affecting neuronal differentiation, represents a third independent risk signal at the SNCA locus. Carriers of risk alleles at rs11931074, rs356219, and rs356182 simultaneously may face substantially elevated cumulative PD susceptibility through three distinct mechanisms — disease risk, elevated expression, and impaired neuronal differentiation — though this triple-carrier scenario has not been formally studied.