Association of genetic variants for plasma LRG1 with rapid decline in kidney function in patients with type 2 diabetes

<b>Abstract</b><b><br></b><b>Context</b>: Elevated levels of plasma Leucine Rich α-2-Glycoprotein 1 (LRG1), a component of TGF-ß signalling, are associated with development and progression of chronic kidney disease in patients with type 2 diabetes (T2D). However, whether this relationship is causal is uncertain. <br> <b>Objectives</b>: To identify genetic variants associated with plasma LRG1 levels and determine whether genetically predicted plasma LRG1 contributes to a rapid decline in kidney function (RDKF) in patients with T2D.<br> <b>Design and participants</b>: We performed a genome-wide association study (GWAS) of plasma LRG1 among 3,694 T2D individuals [1,881(983 Chinese, 420 Malay and 478 Indian) discovery from SMART2D cohort and 1,813 (Chinese) validation from DN cohort]. One- sample Mendelian randomization analysis was performed among 1,337 T2D Chinese participants with preserved glomerular filtration function (baseline estimated glomerular filtration rate (eGFR) &gt;60ml/min/1.73m²). RDKF was defined as an eGFR decline of 3 mL/min/1.73 m²/year or greater.<br> <b>Results: </b>We identified rs4806985 variant near<i> </i>LRG1<i> </i>locus robustly associated with plasma LRG1 levels (MetaP=6.66x10^-16). Among 1,337 participants, 344 (26%) developed RDKF and the rs4806985 variant was associated with higher odds of RDKF (meta odds ratio =1.23, P=0.030 adjusted for age and sex). Mendelian randomisation analysis provided evidence for a potential causal effect of plasma LRG1 on kidney function decline in T2D (P&lt;0.05). <br> <b>Conclusion</b>: We demonstrate that genetically influenced plasma LRG1 increases the risk of RDKF in T2D patients suggesting plasma LRG1 as a potential treatment target. However, further studies are warranted to elucidate underlying pathways to provide insight into DKD prevention.