Chong AS, Nikiforov YE, Condello V, et al. - Researchers conducted this population-based study to determine the prevalence of DICER1 hotspot mutations in thyroid nodules and the frequency of a second DICER1 pathogenic variant in thyroid nodules with DICER1 hotspot mutations, as well as the prevalence of other thyroid cancer driver mutations in thyroid nodules with and without DICER1 hotspot mutations. They analyzed 14,993 consecutive fine-needle aspiration biopsies of thyroid nodules assessed by ThyroSeq v3. Among 14,993 thyroid nodules, 214 (1.4%) showed a DICER1 hotspot mutation. In a proportion of adult thyroid nodules, DICER1 alterations occur and seem mutually exclusive with alterations in other thyroid cancer-related genes. In most cases, DICER1 hotspot mutations occur with a second hit and can indicate occult DICER1 syndrome in adults with thyroid nodules.