TTF1 and Benign familial chorea: Exceptionally, in Benign Hereditary Chorea, a form of non-progressive chorea with normal or mildly reduced cognition, both small and large deletions have been also reported downstream of the causative gene NKX2-1, which encodes for thyroid transcription factor 1 (TTF-1), a protein with a critical role during organogenesis of the basal ganglia, lungs and thyroid.