Key result
Loss-of-function MDA5 variants linked to ~39% lower type 1 diabetes risk but higher IBD risk.
Why the study?
Whether MDA5 loss-of-function variants' associations with protection from type 1 diabetes and increased risk of inflammatory bowel disease are linked or extend to other diseases remains unclear.
Do loss-of-function MDA5 variants protect against autoimmune diseases while increasing the risk of inflammatory bowel disease?
Meta-Analysis (n=801,968)
Do loss-of-function MDA5 variants protect against autoimmune diseases while increasing the risk of inflammatory bowel disease?
Effect estimate: OR 0.611
p-value: p=1.21 x 10^-15
MDA5 genetic variants present a direct fitness trade-off, where loss-of-function variants protect against autoimmune diseases like Type 1 Diabetes but increase the risk of inflammatory bowel disease.
May inform dual autoimmune-IBD risk counseling; leaves open whether MDA5 screening or targeting alters clinical outcomes.
Loss-of-function variants in MDA5, a key sensor of double-stranded RNA from viruses and retroelements, have been associated with protection from type 1 diabetes (T1D) in genome-wide association studies (GWAS). MDA5 loss-of-function variants have also been reported to increase the risk of inflammatory bowel disease (IBD). Whether these associations are linked or extend to other diseases remains unclear. Here, fine-mapping analysis of four large GWAS datasets shows that T1D-protective loss-of-function MDA5 variants also protect against psoriasis and hypothyroidism, while increasing the risk of IBD. The degree of autoimmune protection and IBD risk were linearly proportional. The magnitudes of the odds ratios for autoimmune protection and IBD risk were larger for rare MDA5 variants than for common variants, which were differentially expressed in different geographic populations. Our analysis suggests MDA5 genetic variants offer a direct fitness trade-off between viral clearance and autoimmune tissue damage.
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Wallace et al. (2025) conducted a meta-analysis in Autoimmune diseases and Inflammatory bowel disease (n=801,968). MDA5 loss-of-function variants (e.g., I923V) vs. Reference alleles was evaluated on Risk of Type 1 Diabetes (for I923V variant) (OR 0.611, p=1.21 x 10^-15). Loss-of-function MDA5 variants protected against autoimmune diseases like type 1 diabetes (OR 0.611 for I923V) while proportionally increasing the risk of inflammatory bowel disease (OR 1.318).
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