Is birthweight associated with thyroid autoimmunity? A study in twins

Area of Science:

• Endocrinology
• Immunology
• Genetics

Background:

• Autoantibodies to thyroid peroxidase (TPOAb) and thyroglobulin (TgAb) are key markers of autoimmune thyroid disease.
• While genetic predisposition is recognized, the role of early environmental factors like fetal growth restriction is less understood.

Purpose of the Study:

• To investigate the contributions of genetic and early environmental factors to thyroid autoimmunity.
• To assess the prevalence and concordance of TPOAb and TgAb in a UK twin cohort.

Main Methods:

• A population-based study of monozygous and dizygous twins born in Birmingham, UK (1950-1955).
• Measurement of TPOAb and TgAb using a sensitive immunoprecipitation assay.
• Analysis of concordance rates and prevalence based on zygosity and birth size discordance.

Main Results:

• Higher prevalence of TgAb in monozygous twins compared to dizygous twins.
• Concordance rates for TPOAb and TgAb were higher in monozygous twins, indicating a significant genetic influence.
• Smaller twins within discordant monozygous pairs showed a higher prevalence of TPOAb, suggesting an early environmental impact.

Conclusions:

• Both heritable factors and early environmental influences, such as fetal growth, play a role in susceptibility to thyroid autoimmunity.
• Findings highlight the complex interplay of genetics and environment in the development of autoimmune thyroid disease.