IL-6 Receptor Gene Polymorphism in Idiopathic Nephrotic Syndrome in Kuwaiti Children

Background: Idiopathic Nephrotic syndrome (INS) is an immune-mediated disease in which the many cytokines are involved. IL-6 is a cytokine found to be associated with mesangial diffuse glomerulonephritis and chronic kidney disease. Gene polymorphism of IL-6 receptor (IL-6R) controls the expression and function of IL-6 and may affect the pattern of INS.

Objective: The aim of this study is to determine the frequency and the association of IL-6R gene polymorphisms with idiopathic nephrotic syndrome (INS) and its effect on the disease pattern in Kuwaiti children.

Methods: Genotypes of the IL-6R gene polymorphisms were analyzed using PCR-RFLP in 156 INS patients and 58 age and sex- matched controls. Clinical data of all subjects were reviewed.

Results: A total of 156 INS (131 steroid –sensitive SS&25 steroid resistance SR) patients with a mean age was 7.3±4.0 years were studied. Male: Female ratio was 2:1. The CC genotype of IL-6R gene polymorphism was detected in 75% of the INS patients compared to 69% of the controls (P=0.47). The heterozygous GC genotype was detected in 19% of INS patients compared 27.5% of the controls (P =0.25). The GG-genotype was detected in 5.7% of INS patients and 3.5% of the controls (P =0.73). The C-allele frequency in homozygous and heterozygous forms was found in 94% of INS patients compared to 96.5% of the controls (P =0.73). The G-allele frequency in homozygous and heterozygous forms was found in 25% of INS patients compared to 31% of the controls (P =0.47). No significant difference was found in any of the allele frequencies between SS and & SR sub-groups when compared with each other or when compared to the controls.

Conclusion: Our data shows no role of IL-6 receptor gene polymorphisms on the clinical pattern or response to steroids in Kuwaiti Arab Children with INS.