TSHR and cyclic hematopoiesis: Recently, the OMIM database for genetic disease (at the website www.ncbi.nlm.nih.gov) classified TSH resistance among the six forms of nongoitrous CH (CHNG) and loss-of-function (LOF) mutations in the TSH receptor (TSHR) gene were identified as the most frequent cause of TSH resistance (Table 1) (1,2).