The understanding of the pathophysiology of rheumatoid arthritis (RA) has taken a major step forward with the research of new illness-related genes and further deciphering the involved molecular. Gene variants like human leukocyte antigen (HLA)-DRB1 and PTPN22 1858T act as individual risk factors for RA. It also serves as a risk factor for the rate of progression of joint destruction and clinical manifestations in autoimmune diseases like RA. The focus of this study is to find out the association of chromosomal region 1q21-23 with RA and its connection with disease severity using the disease activity score (DAS) and distribution frequency of the prevalent alleles of such genes in an already recruited group of patients/controls of India, specifically Northwest Rajasthan. This was a case-control study wherein every patient of RA aged 16 years and above diagnosed with RA as per the 2010 American College of Rheumatology (ACR) and the European League against Rheumatism (EULAR) revised criteria for RA in Outpatient Department (OPD) and Inpatient Department (IPD) patients were included. Blood samples of the study population were drawn at Sardar Patel Medical College (SPMC), Bikaner (rheumatology OPD), along with the cooperation of Birla Institute of Technology and Science (BITS), Hyderabad (Department of Biological Sciences) from July 2009 to January 2012. A total of 100 controls (without any previous history of disease) and 135 cases were selected considering inclusion and exclusion criteria. Clinical data along with laboratory parameters like complete blood count, serum electrolytes (sodium, potassium, calcium, and chlorine ions), blood sugar, blood urea with serum creatinine, lactate dehydrogenase (LDH) isoenzymes assay, serum glutamic-oxaloacetic transaminase (SGOT)/serum glutamic pyruvic transaminase (SGPT) ratio, serum γ-glutamyl transferase (GGT) level, serum amylase, arterial blood gas (ABG), total serum proteins were evaluated and recorded from the patients. Our study showed control group has a mean age of 45.11 + 4.12 years. The case and control groups did not have significant differences in any of the clinical variables. 59% of cases show joint deformity. Allelic frequencies of the D1S498 polymorphism in cases were found significant in sizes 198, 204, 208, and 210, while it was found insignificant in sizes 192, 196, 200, 202, and 206. No correlation was found in allelic frequencies of the D1S318 polymorphism in cases and controls. Bigger cohort studies will allow better genomic elucidation of clinically defined intermediate phenotypes evaluated in RA patients by virtue of the autoimmune origin of the disease and its diverse symptoms in patients. Genetic-molecular studies can be a milestone for adopting effective personalized treatment for such progressively debilitating diseases. How to cite this article: Gauri LA, Meena MK, Singh U, et al. Study of Association of Chromosomal Region 1Q21-23 with Rheumatoid Arthritis and Their Correlation with Severity of Disease. J Assoc Physicians India 2023;71(9):28-32.