TSHR and thanatophoric dysplasia: Although most TD cases are sporadic, genetic etiologies involving transcription factors critical for thyroid development [5]—such as TTF1/NKX2.1, PAX8, FOXE1, NKX2-5, and GLIS3—along with mutations in the thyroid-stimulating hormone receptor gene (TSHR), have been identified in approximately 5% of patients [6,7].