Supplementary Material for: Exploring Kidney Injury Molecule-1 and HAVCR1 Polymorphisms as Predictive Biomarkers in Chronic Kidney Disease

Introduction Kidney Injury Molecule-1 (KIM-1), encoded by the Hepatitis A Virus Cellular Receptor 1 (HAVCR1) gene, plays a crucial role in kidney injury progression. Although serum and urinary KIM-1 levels are established biomarkers for kidney damage, the relationship between KIM-1 levels, HAVCR1 gene polymorphism, and chronic kidney disease (CKD) stages remains unclear. This study aimed to investigate KIM-1 as a potential biomarker for CKD progression in the Thai population and explore its association with genetic polymorphisms in the HAVCR1 gene. Methods A total of 250 patients with CKD were recruited from Khon Kaen, Thailand. Serum and urinary KIM-1 levels were measured using an indirect enzyme-linked immunosorbent assay. Single-nucleotide polymorphism (SNP) genotyping was conducted using the TaqMan assay to assess the associations between KIM-1 levels, SNPs, and CKD progression. Statistical analyses were conducted to assess the correlations between estimated glomerular filtration rate (eGFR), KIM-1 levels, and SNPs. Results Serum and urinary KIM-1 levels showed a significant negative correlation with eGFR, indicating higher KIM-1 levels in patients with more advanced CKD. However, the rs6555820 SNP in the HAVCR1 gene did not show a significant association with KIM-1 levels or eGFR. Interestingly, a significant association between rs6555820 and gender was observed, implying a potential gender-dependent genetic impact. Conclusion Serum and urinary KIM-1 levels have been found to be associated with CKD stages and eGFR, suggesting their potential as biomarkers for assessing CKD severity. However, no direct associations were observed between the SNP rs6555820 and KIM-1 levels or eGFR. Further research is required to elucidate the genetic mechanisms underlying CKD progression.