Definition:

Benign hereditary chorea (BHC) is a rare, autosomal dominant, static disorder characterized by onset of chorea in conjunction with hypothyroidism and respiratory problems. Features supporting this diagnosis include normal general examination with no dysmorphic features, broadly normal intellectual development with no regression or loss of cognitive skills, absence of other significant neurologic disturbances, and, with the exception of chorea, normal neurologic examination findings. Mutations in the TTF1 gene encoding the thyroid transcription factor-1 have been identified in a number of BHC patients, suggesting that aberration of TTF1 transcriptional function or haploinsufficiency is associated with this disorder. TTF1, belonging to the NKX2 homeodomain transcription factor family, has been implicated in several important molecular pathways essential for brain, thyroid and lung morphogenesis.