Abstract

Benign Hereditary Chorea ( BHC) is a very rare autosomal dominant condition. It is characterised by an early onset, non-progressive form of chorea and is not associated with intellectual deterioration. This condition is caused by mutation in the thyroid transcription factor-1 gene (TTFI-1). The proband of this family affected with BHC presented in infancy with delayed walking and ataxic features, then chorea and she later developed hypothyroidism aged 33. On imaging, aged 41, she was found to have a large cystic pituitary mass, which has remained stable on MRI over a 3 year period. She has never experienced any respiratory symptoms and her spirometry is normal. She therefore does not full fill the criteria for the Brain-Lung-Thyroid syndrome that has been reported with certain mutations of the TITF-1 gene. Genetic testing showed that the proband carries a novel mutation in TITF-1. The same TITF-1 mutation was transmitted to her only child. This child was also affected and presented in infancy with delayed walking and non progressive chorea, but has developed no additional features. Genetic analysis of the whole family including both parents and siblings of the proband confirm that the mutation arose de novo. This newly identified mutation causes Benign Familial Chorea, hypothyroidism and a pituitary mass with no respiratory component. We discuss the effects of this new mutation, and propose mechanisms of pathogenesis that may account for the discrete signs and symptoms seen in this disorder.