Anti-thyroid peroxidase (anti-TPO) has been detected in ~10–16 % of all pregnant women tested (146, 148) and in 80% of women who were screened specifically for GDM; however only 26% of all women who exhibited anti-TPO in their blood had a GDM diagnosis according to WHO criteria (149), suggesting that measurement of anti-TPO antibodies has low specificity for GDM screening. The gene discussed is TPO; the disease is gestational diabetes.