Retinoid related orphan receptor alpha (ROR alpha) is a NR1 Thyroid Hormone Like Receptor. Three different subtypes ROR alpha, beta, and gamma have been discovered. ROR alpha plays a key role in the development of the cerebellum. Deletion of ROR alpha in mice causes severe impairment in the differentiation of cerebellar Purkinje neurons and results in the "staggerer" phenotype. ROR alpha has been suggested in the regulation of a number of other physiological processes, including bone formation. Recently, ROR alpha was reported to regulate lymphocyte development and mediate Th17 differentiation synergistically with ROR gamma.