When one member of a family develops lupus, another rheumatoid arthritis and a third an autoimmune muscle disorder, the question that often arises is whether there is a common link. Why do autoimmune diseases appear in some families, and why do certain relatives remain unaffected despite sharing the same family background?
A new four-year, ICMR-funded research project involving AIIMS, New Delhi, and five other medical centres aims to investigate these questions. Researchers plan to study 200 families across the country to identify genetic and immune-related factors that may make some families more vulnerable to autoimmune diseases.
The study is particularly relevant for families in which at least three members have autoimmune diseases, including at least one person with systemic lupus erythematosus (SLE), commonly known as lupus. At least two unaffected family members must also be available to participate. The research team will assess whether families meet the eligibility criteria.
The project will examine conditions beyond lupus. Affected relatives may have diseases such as myositis, Sjögren’s syndrome, type 1 diabetes or vitiligo. The researchers will compare affected and unaffected members of the same family to understand why different people may develop different conditions, or remain healthy.
The proposed study builds on earlier evidence that autoimmune diseases can cluster within families.
A 2019 study published in Rheumatology International, titled Study of familial aggregation of autoimmune rheumatic diseases in Asian Indian patients with systemic lupus erythematosus, examined the family histories of 157 people with lupus at Christian Medical College, Vellore.
Researchers found autoimmune rheumatic diseases in the families of 39 patients, amounting to a familial prevalence of 24.8%. Lupus was the most frequently reported autoimmune rheumatic disease, appearing in 19 families (12.1%). Rheumatoid arthritis was the second most common, reported in 16 of the 39 families with autoimmune rheumatic diseases.
The study also found that first-degree relatives — parents, siblings and children — had a higher familial aggregation of these conditions than more distant relatives.
These findings suggest that family history can be an important clue in understanding autoimmune disease susceptibility. However, the study was hospital-based and included families of people already diagnosed with lupus. Its findings should not be interpreted as the risk faced by every Indian family or as proof that the diseases are inherited in a predictable way, said the researchers.
A more recent multicentre study, published in 2026, examined family histories among patients with rheumatoid arthritis, lupus and systemic sclerosis using data from the Indian Rheumatology Association database.
Among patients for whom family-history information was available, 19.6% of those with rheumatoid arthritis, 11.4% of those with lupus and 10% of those with systemic sclerosis reported a family history of autoimmune disease. First-degree relatives accounted for most of the reported familial cases. The researchers also observed disease-specific patterns, suggesting that relatives may develop the same or different autoimmune conditions.
Autoimmune diseases develop when the immune system mistakenly attacks the body's own cells and tissues. They include a wide range of conditions affecting different organs, from lupus and rheumatoid arthritis to type 1 diabetes and certain thyroid disorders.
Genes can influence susceptibility, but carrying a genetic variation does not automatically mean that a person will develop the disease. Environmental exposures and differences in immune responses may also influence whether the condition develops.
“Genetics alone does not explain why everyone carrying a particular genetic marker does not develop the disease,” Dr Ranjan Gupta, additional professor in the department of rheumatology at AIIMS, said while explaining the rationale behind the study. Environmental influences and differences in immune responses may also play a role, he said.
The research team will collect blood samples from affected and unaffected relatives and examine genetic variations, cytokine profiles and other biological markers. Comparing these findings may help identify shared biological mechanisms behind different autoimmune conditions.
The broader aim is to identify potential biomarkers and biological pathways that could guide future research into disease risk and treatment. The study is not a screening programme and cannot currently predict whether an unaffected relative will develop an autoimmune condition.
The project will involve AIIMS, New Delhi; Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow; St John's Medical College, Bengaluru; Nizam's Institute of Medical Sciences, Hyderabad; Medical College, Kolkata; and AIIMS Bibinagar, Telangana. The research will be coordinated with Ashoka University, Sonipat.
Researchers are inviting eligible families, particularly those in Delhi and the National Capital Region, to contact the AIIMS team. Patients receiving treatment at other hospitals may also express interest. Participation will depend on the research team's assessment of the family's eligibility and informed consent from those taking part.
