SLC6A4 and thyroid gland disorder: Genetic mutations associated with hypothyroidism are related to thyroid dysgenesis-related genes, such as thyroid-stimulating hormone receptor (TSHR), Forkhead Box E1 (FOXE1), NK2 Homeobox 1 (NKX2-1), Paired Box 8 (PAX8), and NK2 Homeobox 5 (NKX2-5), as well as thyroid dyshormonogenesis linked genes, such as Solute Carrier Family 5 Member 5 (SLC5A5), Thyroid Peroxidase (TPO), Dual oxidase 2 (DUOX2), Dual oxidase maturation factor 2 (DUOXA2), Solute Carrier Family 6 Member 4 (SLC6A4), and iodothyronine dehalogenase (DEHAL1) [6,7].