There are more than 80 recognised autoimmune diseases, and they range from organ-specific disorders to systemic diseases affecting multiple tissues. Examples commonly discussed by major medical research organisations include type 1 diabetes, rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, Sjögren's disease, scleroderma, vitiligo, alopecia areata, pemphigus and psoriasis. The word “common” can be misleading because prevalence varies by country, age, sex and diagnostic criteria, and some conditions that are familiar to the public are considerably more prevalent than others. Autoimmune diseases can affect almost any organ system, and several share symptoms such as fatigue, pain and inflammation, which can make diagnosis difficult.
Rheumatoid arthritis is a systemic autoimmune inflammatory disease in which immune-mediated inflammation primarily affects the synovial lining of joints, producing pain, swelling, stiffness and progressive structural damage if inadequately controlled. It can also affect tissues outside the joints, including the lungs, eyes, skin and cardiovascular system. The disease is associated with autoantibodies such as rheumatoid factor and anti-cyclic citrullinated peptide antibodies, although these tests are not individually sufficient to diagnose every patient. Treatment aims to suppress pathological inflammation and prevent irreversible joint damage, often using disease-modifying antirheumatic drugs and targeted biological or synthetic therapies. Its importance as an autoimmune disease therefore extends beyond ordinary mechanical arthritis.
Systemic lupus erythematosus, usually called lupus or SLE, is a systemic autoimmune disease capable of affecting skin, joints, blood cells, kidneys, lungs, heart and nervous tissue. It involves abnormal immune recognition and production of autoantibodies, with immune complexes and inflammatory pathways contributing to tissue injury. Symptoms can vary markedly between individuals and may fluctuate over time, which contributes to diagnostic complexity. Kidney involvement can be particularly important because lupus nephritis may impair renal function if significant inflammation is not recognised and treated. Lupus illustrates the distinction between organ-specific and systemic autoimmunity because the immune process is not confined to one anatomical structure.
Type 1 diabetes is an autoimmune disease in which immune-mediated destruction of pancreatic beta cells reduces or eliminates the body's ability to produce sufficient insulin. Unlike type 2 diabetes, which primarily involves insulin resistance and progressive beta-cell dysfunction, type 1 diabetes is characterised by autoimmune targeting of insulin-producing cells and requires insulin replacement for survival. Disease development involves genetic susceptibility and environmental influences, although the precise initiating events are not fully understood. The condition demonstrates that autoimmune disease can produce its major clinical effects through loss of a specialised cell population rather than through obvious inflammation in the affected organ.
Multiple sclerosis is an immune-mediated disease of the central nervous system in which immune processes contribute to injury involving myelin, oligodendrocytes and, in some circumstances, axons and other neural structures. The resulting neurological manifestations depend on which parts of the brain, spinal cord or optic pathways are affected and may include visual disturbance, weakness, sensory changes, balance problems and cognitive symptoms. Multiple sclerosis commonly follows a relapsing-remitting pattern early in its course, although progressive forms also occur. Research has identified strong associations with genetic susceptibility and environmental factors, including evidence implicating Epstein-Barr virus as an important contributor to disease development, while the exact causal pathway remains an active research area.
Sjögren's disease is an autoimmune disorder in which immune cells target glands responsible for producing moisture, particularly the lacrimal and salivary glands. The resulting dryness can affect the eyes and mouth and may lead to dental problems, difficulty swallowing or speaking, eye irritation and other systemic manifestations. Some people also develop fatigue, joint symptoms, nerve involvement, lung disease or other complications. Scleroderma, or systemic sclerosis, is another autoimmune condition characterised by abnormal immune activity, vascular abnormalities and excessive fibrosis, producing thickened or hardened skin and potentially affecting internal organs. Both conditions demonstrate that autoimmune diseases can involve combinations of immune, vascular and connective-tissue abnormalities rather than a single inflammatory mechanism.
Vitiligo and alopecia areata illustrate autoimmune diseases affecting specialised cells or structures in the skin. Vitiligo occurs when immune mechanisms destroy melanocytes, producing areas of depigmented skin. Alopecia areata involves immune attack on hair follicles and causes patchy or more extensive hair loss. Psoriasis is an immune-mediated inflammatory skin disease characterised by accelerated skin-cell turnover and chronic inflammation; although its classification and immunological mechanisms are more complex than a simple “self-attack” model, immune pathways are central to the disease. These conditions show why autoimmune and immune-mediated inflammatory disorders can have very different visible manifestations even when abnormal immune regulation is involved.
Other autoimmune or immune-mediated diseases include autoimmune thyroid disorders, autoimmune hepatitis, inflammatory bowel conditions with immune-mediated components, myositis, vasculitis and various forms of autoimmune blistering disease. Some conditions primarily target one organ, while others have systemic manifestations. Classification can also change as researchers discover molecular mechanisms; diseases once grouped primarily by symptoms may be subdivided according to immune pathways or genetic characteristics. “Common autoimmune disease” therefore does not represent one fixed list. The most important established examples include rheumatoid arthritis, lupus, type 1 diabetes and multiple sclerosis, while numerous less prevalent conditions can nevertheless cause serious disease.
