SLC16A2 and cyclic hematopoiesis: CH may be caused by abnormal development or function of thyroid gland (primary CH), or by dysfunction of hypothalamus or pituitary gland (central CH), or more rarely by impaired transport or action of thyroid hormone at the tissue level, such as monocarboxylate transporter 8 defects or Alan–Herndon–Dudley syndrome, resistance to thyroid hormone alfa (RTHα) or resistance to thyroid hormone beta (RTHβ) [1,2,3].