GNAS and adenocarcinoma: Strikingly, only 2 HT cats in our study lacked Gsα mutations, HT02 and HT11, of which HT02 was confirmed to be a case of adenocarcinoma, and HT11 was grade 3, the lowest grade of the clinically HT cats included in the RNA-seq. Notably, however, HT11 thyroid tissue carried both p.D632Y/H and p.M727V TSHR mutations, and therefore the potential involvement of TSHR mutations in some cases of FHT warrants further study.