Stoppa-Vaucher S, Van Vliet G, Deladoëy J. Variation by Ethnicity in the Prevalence of Congenital Hypothyroidism due to Thyroid Dysgenesis. Thyroid 2011; 21(1):13-8. Thyroid dysgenesis is less prevalent in Blacks and more prevalent in Caucasians. Blacks being more genetically diverse, this suggests oligogenic mechanisms accounting for thyroid dysgenesis.