Genetic Polymorphism and serum levels of Insulin like Growth Factor-1 (Igf-1) in patients of rheumatoid arthritis

Objectives: Insulin like growth factor-1(IGF-1), is a modulator of immunity and inflammation, it promotes the anabolic role of growth hormone (GH) on bone and skeletal tissue. Genetic polymorphism in IGF-1 gene is reported to affect the transcriptional efficiency affecting its serum level. In this study we aim: 1) To study the presence of 192bp polymorphism of IGF-1 gene in patients of rheumatoid arthritis (RA), 2) To study the association of 192 bp polymorphism of IGF-1 gene with serum IGF-1 levels and disease severity in patients of RA.

Methods: A cross-sectional study was carried out at University of Health Sciences (UHS), Lahore. Diagnosed RA cases who fulfilled the American College of Rheumatology (ACR) criteria were recruited from Fatima Memorial Hospital (FMH) and Behbud Rheumatology Clinics, Lahore during 2018–2019. Serum IGF-1 levels were determined by ELISA in blood samples of 200 RA patients and 200 healthy individuals. DNA was extracted and genetic polymorphism was determined.

Results: The serum IGF-1 level in RA group was significantly lower compared to healthy group. Our study shows presence of 192bp allele of IGF-1in 77% of the studied population. Carriers of 192bp allele of IGF-1 had a significantly higher serum level of IGF-1 as compared to non-carriers in the RA patients. Rheumatoid factor (RF) positive patients had a higher number of 192bp carriers in comparison to RF negative patients. Significant difference was also seen in severity of disease between carrier and non-carriers of 192bp allele with the disease being more severe in male carriers.

Conclusions: There is an association of IGF-1gene polymorphism with variation in serum IGF-1 levels and severity of RA.