SLC16A2 and cyclic hematopoiesis: However, no consensus has been reached yet to screen more rare forms of CH, such as Allan–Herndon–Dudley syndrome (AHDS), an X-linked condition linked to mutations in the gene encoding a transmembrane monocarboxylate transporter (MCT8), resistance to thyroid hormone beta (RTHβ), and resistance to thyroid hormone alfa (RTHα).