Familial Risk of Hashimoto's Thyroiditis in a Large Genealogical Database.

Area of Science:

• Endocrinology
• Genetics
• Epidemiology

Background:

• Hashimoto's thyroiditis (HT) is an autoimmune thyroid disorder affecting 5% of the US population.
• First-degree relatives of HT patients have a 4.5 to 32 times higher risk.
• High heritability of HT is estimated at approximately 65% from twin studies.

Purpose of the Study:

• To estimate the relative risk (RR) of developing HT in first-, second-, and third-degree relatives.
• To analyze familial risk using the Utah Population Database (UPDB).

Main Methods:

• Utilized the Utah Population Database (UPDB).
• Identified 92,405 HT probands and 184,810 matched controls.
• Analyzed 2,960,650 relatives of HT probands and 5,730,159 relatives of controls.

Main Results:

• Females were 2.71 times more likely to have HT than males.
• Odds ratio (OR) for first-degree relatives was 1.77 (95% CI 1.74-1.80).
• OR for second-degree relatives was 1.23 (95% CI 1.22-1.27), and for third-degree relatives was 1.11 (95% CI 1.10-1.12).
• Increased OR for spouses (1.50-1.58) suggests an environmental component.

Conclusions:

• This study provides the first estimates of HT risk for second- and third-degree relatives.
• The findings suggest both genetic and environmental factors contribute to HT development.
• Familial risk extends beyond first-degree relatives, highlighting broader genetic or shared environmental influences.