Possible causes of thyroid dysgenesis include the impact of maternal antithyroid immunoglobulins, genetic mutations, genes of transcription factors TTF1, TTF2 and PAX8, and HHEX found in functional thyroid cells, but also in their precursors, which are essential for the early stages of thyroid morphogenesis [4,5]. The gene discussed is PAX8; the disease is thyroid gland disorder.