RORA and osteoporosis: RORα-deficient mice that carry a natural deletion in the ligand-binding domain have cerebellar ataxia, a phenotype also observed in Staggerer (sg/sg) mutant mice [12], which express mutated RORα and additionally present vascular dysfunction, muscular defects, osteoporosis, immune abnormalities, and diet-induced atherosclerosis [13–15].