rs35333564 — MIR4300HG AIS Progression Locus (intron 1 enhancer indel)

MIR4300HG — The Non-Coding Switch for Spinal Curve Progression

Adolescent idiopathic scoliosis (AIS) affects 2–3% of the population and is characterized by a lateral curvature of the spine with no clear structural or neuromuscular cause. Most cases are mild and never require intervention, but roughly 10% of affected adolescents experience progressive curves that exceed 40–50 degrees and require bracing or surgery. The genetic factors that determine who progresses and who stabilizes have long been elusive. This variant sits at the center of one of the strongest progression-specific genetic signals yet identified.

MIR4300HG is the host gene for microRNA MIR4300¹¹ microRNA MIR4300
a small non-coding RNA whose primary role is post-transcriptional gene regulation — it binds to the 3′ UTR of target mRNAs and suppresses their translation. MIR4300HG is most highly expressed in testis, followed by spinal cord, bone, vertebral disc, and cartilage — precisely the tissues involved in scoliotic deformity.

The Mechanism

rs35333564 is a single-nucleotide indel in a homopolymeric G-run (GGG→GG) in intron 1 of MIR4300HG. Luciferase reporter and electrophoretic mobility shift assays²² Luciferase reporter and electrophoretic mobility shift assays
laboratory techniques for measuring transcriptional activity and protein-DNA binding showed that the region containing rs35333564 has enhancer activity, and that the risk allele (the intact GGG sequence, the less common allele) significantly reduces this enhancer function compared to the deletion allele. The mechanism is likely related to altered transcription factor binding — EMSA showed allele-specific differences in protein-DNA binding at this exact position.

The result is lower expression of MIR4300 in individuals carrying the risk allele. Wang et al. 2021³³ Wang et al. 2021 confirmed in 76 paraspinal muscle biopsy samples that the GGG homozygote genotype was associated with significantly reduced MIR4300 expression (p=0.020), and that MIR4300 expression levels correlated inversely with Cobb angle magnitude (p=0.010). The paper also identified CRTC1 (CREB-regulated transcription coactivator 1) as a candidate downstream target of MIR4300 regulation: CRTC1 expression was negatively correlated with MIR4300 (p=0.012) and positively correlated with curve severity (p=0.025), suggesting a pathway from reduced MIR4300 → elevated CRTC1 → progressive curvature.

The Evidence

Ogura et al. 2017 in Human Molecular Genetics⁴⁴ Ogura et al. 2017 in Human Molecular Genetics performed a GWAS specifically for AIS curve progression (not susceptibility) in 2,543 Japanese AIS subjects and identified rs35333564 as the functional variant within the associated locus. The combined odds ratio was 1.56 (95% CI 1.35–1.80) with a genome-wide significant P-value of 1.98×10⁻⁹. The association was with curve progression rather than with AIS onset, making it clinically distinct from the many susceptibility loci already in the literature.

Wang et al. 2021⁵⁵ Wang et al. 2021 replicated this finding in a Chinese cohort (1,952 AIS patients vs. 2,495 controls; 747 progressive vs. 520 non-progressive), confirming that rs35333564 was significantly associated with curve severity (p=0.025) but not with AIS development (p=0.418). This susceptibility-vs.-progression distinction is important: the variant does not increase your chance of developing AIS, but does affect how severe curves may become in those who have it.

Dai et al. 2025 in Spine⁶⁶ Dai et al. 2025 in Spine evaluated 259 female AIS patients undergoing brace treatment and found no significant association between rs35333564 and bracing outcome. This suggests the variant influences natural history of curve progression but does not predict responsiveness to mechanical correction.

The risk allele shows notable population stratification: it is approximately 5× more common in East Asian populations (~19%) than in Europeans (~4%), broadly consistent with higher AIS prevalence and progression rates observed in East Asian cohorts.

Practical Actions

For adolescents diagnosed with AIS who carry one or two copies of the risk allele, the main implication is heightened vigilance for curve progression during the growth spurt years. Orthopedic monitoring should follow the curve trajectory closely. Earlier initiation of brace therapy at lower Cobb angles may be warranted in progressive-allele carriers, since bracing is most effective before curves reach 40 degrees. Vitamin D and calcium adequacy support bone density and spinal development during adolescent growth, and deficiency of either can independently worsen scoliotic outcomes.

Currently there are no supplements or dietary interventions that directly target the MIR4300/CRTC1 pathway. Management is through orthopedic monitoring and timely intervention.

Interactions

rs1828853 is the GWAS index SNP for this locus (r²≥0.8 with rs35333564) and is also located in MIR4300HG intron 1. The two variants are in strong LD; rs35333564 is the functional variant confirmed by the molecular assays. No interactions with other scoliosis susceptibility loci (LBX1 rs11190870, GPR126 rs6570507, BNC2 rs10738445) have been directly tested for rs35333564.