ESRRA and osteopetrosis: Researchers verified the role of ERRα in osteoclasts in ERRα-KO mice and showed that ERRα deletion disrupted the expression of several major genes in cells, and ERRα-KO mice exhibited osteopetrosis due to osteoclast defects and decreased bone resorption, suggesting that ERRα may be a significant regulator of osteoclastogenesis (Yang and Wan 2019).