rs1414273 — CD58

CD58 rs1414273 — The miR-548ac Switch That Defines the MS-Risk Haplotype

Every CD58 intronic variant associated with multiple sclerosis risk — rs2300747, rs12044852, rs1016140, rs1335532 — sits within the same tightly linked haplotype block in the first intron of CD58 on chromosome 1. Among them, rs1414273 holds a mechanistically unique position¹¹ rs1414273 holds a mechanistically unique position
rs1414273 lies directly within the hairpin sequence of hsa-miR-548ac, the microRNA co-encoded from the same primary transcript as CD58 mRNA: it is the functional anchor through which the risk haplotype disrupts the balance between CD58 and an immunoregulatory microRNA.

CD58, also known as LFA-3 (Lymphocyte Function-Associated Antigen 3)²² LFA-3 (Lymphocyte Function-Associated Antigen 3)
LFA-3 is a glycoprotein expressed on antigen-presenting cells and non-immune tissues; it binds CD2 on T cells to stabilise the immune synapse and transmit co-stimulatory signals that licence regulatory T cell induction, governs whether a T-cell encounter with an antigen-presenting cell produces immune tolerance or inflammatory activation. This signalling axis sits at the centre of multiple sclerosis genetics: the CD58 locus is one of the most robustly replicated non-HLA MS susceptibility regions.

The Mechanism

The miR-548ac gene is embedded within CD58 intron 1. Like all microRNAs, it begins as part of a longer primary transcript (pri-miRNA) that is cropped by the nuclear Drosha-DGCR8 endonuclease complex³³ Drosha-DGCR8 endonuclease complex
Drosha cleaves the pri-miRNA at the base of the hairpin stem-loop to release the 60–70 nt precursor (pre-miRNA), which is then exported to the cytoplasm and processed by Dicer into the mature ~22 nt miRNA. Because CD58 mRNA and miR-548ac are transcribed from the same genomic locus, Drosha cleavage efficiency has a reciprocal effect: more efficient cleavage favours miR-548ac production at the expense of full-length CD58 mRNA reaching the cytoplasm for translation.

rs1414273 sits at the precise base of the miR-548ac stem-loop. The reference allele is C on the plus strand — corresponding to G on the coding (minus) strand — which pairs with a uridine in the opposite strand of the hairpin to form a G-U wobble base pair. The alternate T allele (coding-strand A) forms an A-U Watson-Crick base pair, which is less efficiently recognised by Drosha. The consequence:

• C allele (risk): G-U wobble → enhanced Drosha recognition → more miR-548ac, less CD58 mRNA
• T allele (protective): A-U Watson-Crick → reduced Drosha efficiency → less miR-548ac, more CD58 mRNA

In cell-culture experiments, the G-containing construct (risk allele) produced 1.5-fold more mature miR-548ac at 24 hours and 3.4-fold more at 48 hours compared to the A-containing construct, after normalisation to precursor RNA. In population-level eQTL analyses spanning HapMap, Geuvadis, and MS patient cohorts, risk allele carriers showed significantly lower CD58 transcript levels and significantly higher miR-548ac levels⁴⁴ risk allele carriers showed significantly lower CD58 transcript levels and significantly higher miR-548ac levels
The paradoxical inverse relationship between CD58 mRNA and miR-548ac co-encoded from the same locus is explained by Drosha-mediated uncoupling: cleavage of the stem-loop interrupts full-length mRNA synthesis while liberating the microRNA hairpin.

miR-548ac targets validated in this mechanistic framework include SDC4 (syndecan-4)⁵⁵ SDC4 (syndecan-4)
SDC4 regulates T-cell motility and heparan sulfate proteoglycan signalling, SEL1L⁶⁶ SEL1L
SEL1L participates in endoplasmic reticulum-associated protein degradation (ERAD) and proteostasis under inflammatory stress, and TNFAIP3 (A20)⁷⁷ TNFAIP3 (A20)
TNFAIP3/A20 is a master ubiquitin-editing enzyme that terminates NF-κB signalling; miR-548ac-mediated suppression of A20 would sustain inflammatory NF-κB activity. A broader computational screen identified 333 predicted miR-548ac targets enriched in cytokine signalling, MAPK pathways, and protein folding — consistent with a broadly immunomodulatory role for this microRNA.

The Evidence

The functional significance of rs1414273 was first proposed by Galarza-Munoz et al. 2015⁸⁸ Galarza-Munoz et al. 2015
1000 Genomes sequencing data used to identify rs1414273 as the only SNP at the base of the miR-548ac stem-loop in strong LD with the MS-associated haplotype, who recognised that its position within the Drosha recognition element made it a strong candidate for the causal variant within the CD58 MS locus.

The full mechanistic and eQTL evidence was published by Hecker et al. 2019 PLoS Genetics⁹⁹ Hecker et al. 2019 PLoS Genetics
Expression QTL analysis across >1,000 subjects from HapMap and Geuvadis cohorts combined with in vitro Drosha cleavage experiments and real-time PCR of 32 MS patients. This study demonstrated both the population-level expression effects and the molecular mechanism in a single unified study, making rs1414273 the best-characterised functional variant at the CD58 MS locus.

The variant is in near-complete LD (r² ≈ 1, D' ≈ 1) with rs1335532, the GWAS lead SNP for the CD58 MS locus in European cohorts. Correlated alleles on the forward strand are: rs1414273 C = rs1335532 A (both risk alleles); rs1414273 T = rs1335532 C (both protective alleles). This tight LD means rs1414273 and rs1335532 are functionally interchangeable for GWAS-level MS association signals, but rs1414273 uniquely maps the molecular effect to Drosha recognition.

Population genetics provide an instructive layer. The C (risk) allele is the major allele in Europeans (~87%) — matching the high-frequency risk pattern seen throughout the CD58 locus (rs12044852, rs2300747). In contrast, East Asian and African populations carry the T (protective) allele at ~59% and ~51% respectively. This mirrors the population-level MS burden: the disease is considerably rarer in East Asian populations where the protective T allele predominates.

A pilot replication study in a Malaysian/Kuwaiti cohort found CD58 rs1414273 to be significantly associated with MS in an Arab population (p = 0.00007, OR 2.2, 95% CI 1.5–3.2 in exome analysis), though a separate genotyping-only Kuwaiti replication did not reach significance, likely reflecting population-specific LD structure between rs1414273 and the GWAS signals.

Practical Actions

Since the C allele is the major allele in Europeans (~87%), CC homozygotes represent the largest fraction of the population — and carry the highest miR-548ac burden and lowest CD58 expression at this locus. There is no supplement that directly inhibits miR-548ac or compensates for reduced CD58, but vitamin D is the best-characterised modifiable factor that supports FoxP3+ regulatory T cell function¹⁰¹⁰ FoxP3+ regulatory T cell function
FoxP3 is the master transcription factor for Tregs; vitamin D drives FoxP3 expression via VDR binding at the FoxP3 promoter, providing a parallel Treg-supporting input to the CD58 co-stimulatory signal through mechanisms independent of CD58.

Interactions

rs1414273 is in near-complete LD with rs1335532 and is strongly correlated with rs12044852 (r² = 0.929 between rs12044852 and rs2300747, with rs1414273 in the same haplotype). The four CD58 intronic variants — rs2300747, rs12044852, rs1016140, rs1414273 — collectively define the CD58 MS-risk haplotype. The rs1016140 G allele has an independent signal for NMO risk and autoimmune thyroid disease via a mechanistically distinct direction, illustrating that the intronic haplotype block contains variants with both shared and divergent functional effects.

miR-548ac's validated target TNFAIP3 (A20) connects this variant to the NF-κB inflammatory pathway, creating a potential interaction with cytokine-pathway SNPs (e.g. TNFRSF1A rs1800693 in the same immune-gut category).