Pharmacogenetics of Leflunomide in the Management of Rheumatoid Arthritis

This study is looking at how genetics influence how patients with rheumatoid arthritis (RA) respond to leflunomide, a medication commonly used to reduce joint inflammation. By understanding these genetic differences, doctors may be able to predict who will benefit from or experience side effects from this drug. **You may be eligible if...** - You are between 20 and 75 years old - You are Pakistani - You have been diagnosed with rheumatoid arthritis according to established criteria - You are either starting leflunomide for the first time or have been on it for less than one month, and your clinical data is available **You may NOT be eligible if...** - You are unwilling to participate or give consent - You are under 20 years of age - You are not of Pakistani origin - You are currently taking another disease-modifying drug (DMARD) alongside leflunomide - You have kidney or liver problems - You have cognitive impairment or a neurological disease - You are pregnant or breastfeeding - You have inflammatory bowel disease or irritable bowel syndrome - You have an active infection - You fail to complete 3 months of leflunomide therapy Talk to your doctor to see if this trial is right for you.