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Sex ratio and rheumatic disease
1Barbara Volcker Center, Hospital for Special Surgery, Joan and Sanford I. Weill Medical College, Cornell University, New York, USA. LockshinM@hss.edu
The Israel Medical Association Journal : IMAJ
|January 17, 2002
Summary
Autoimmune disease sex ratios are imprecise, varying widely across studies. Explanations for female predominance may involve environmental factors or developmental influences rather than hormone levels.
Area of Science:
- Immunology
- Epidemiology
- Genetics
Background:
- Autoimmune diseases exhibit significant sex-based incidence disparities, often with higher rates in females.
- Existing data on female/male (F/M) ratios for autoimmune conditions are inconsistent due to varying definitions and classifications.
- Precise understanding of the causality behind these sex differences is lacking.
Purpose of the Study:
- To critically evaluate the precision of reported female/male ratios in autoimmune diseases.
- To explore potential underlying mechanisms contributing to sex-based incidence differences in autoimmune conditions.
- To differentiate between incidence and severity in sex-discrepant autoimmune diseases.
Main Methods:
- Systematic review of published literature on autoimmune disease classifications and reported F/M ratios.
- Comparative analysis of F/M ratios across different autoimmune disease categories (e.g., thyroid, rheumatic, hepatic).
- Theoretical exploration of potential sex-determining factors beyond gonadal hormones.
Main Results:
- Reported F/M ratios for autoimmune diseases are highly variable and often imprecise.
- Certain conditions like thyroid, rheumatic, and hepatic autoimmune diseases consistently show high F/M ratios, though specific values differ.
- Some autoimmune diseases present with low F/M ratios, challenging a universal female predominance.
- F/M ratios primarily reflect disease incidence, not necessarily severity.
Conclusions:
- The imprecision in F/M ratios necessitates refined diagnostic criteria and epidemiological studies.
- Gonadal hormones may play a permissive or threshold role, but other factors are likely key.
- Alternative explanations for female predominance include environmental exposures, X-inactivation, imprinting, chromosomal influences, and intrauterine factors.
- The epidemiology of female-predominant autoimmune diseases suggests that differential exposure, critical developmental periods, or threshold effects are more plausible than quantitative immunomodulation differences.