Twin studies in auto-immune disease

Area of Science:

• Immunology
• Genetics
• Epidemiology

Background:

• Immune-mediated diseases affect up to 5% of the population, causing significant morbidity and mortality.
• These diseases can be organ-specific (e.g., insulin-dependent diabetes) or non-organ-specific (e.g., Rheumatoid Arthritis).
• Twin studies are crucial for distinguishing genetic from environmental contributions to disease etiology.

Purpose of the Study:

• To analyze twin study data on immune-mediated diseases to determine the interplay of genetic and environmental factors.
• To investigate the role of HLA genes and non-genetic factors in disease susceptibility.
• To identify predictive markers of clinical disease by studying high-risk, unaffected co-twins.

Main Methods:

• Collated and analyzed results from twin studies on diseases including IDDM, RA, SLE, MS, and Myasthenia.
• Compared concordance rates between identical and non-identical twins.
• Examined unaffected co-twins of affected individuals to identify pre-clinical changes.

Main Results:

• Significant differences in concordance rates between identical and non-identical twins indicate a strong genetic component.
• Association with HLA genes on chromosome 6 suggests a role in genetic susceptibility.
• The majority of affected twins have unaffected co-twins, highlighting the critical role of non-genetic, likely environmental, factors.

Conclusions:

• Genetic factors are important, but environmental influences are critical in the majority of immune-mediated diseases.
• Studying unaffected co-twins can identify pre-clinical changes and predict disease onset.
• Identical twins offer a valuable model for investigating the role of T-cells in immune-mediated diseases.