Benign hereditary chorea

Benign hereditary chorea (BHC), also known as hereditary nonprogressive chorea, is a rare genetic movement disorder caused primarily by mutations in the NKX2-1 gene (also called TITF1 or TTF-1) on chromosome 14q13.3. This gene encodes thyroid transcription factor 1, which plays a critical role in the development of the brain, thyroid gland, and lungs. BHC is characterized by early-onset choreiform movements — involuntary, irregular, rapid movements — that typically begin in infancy or early childhood, usually around the time a child begins to walk. Unlike Huntington disease, BHC is nonprogressive or may even improve with age, and it does not cause cognitive decline or dementia. The condition primarily affects the nervous system, but because NKX2-1 is expressed in multiple organs, patients may also present with thyroid dysfunction (congenital hypothyroidism) and pulmonary problems (infant respiratory distress syndrome, recurrent pulmonary infections, or interstitial lung disease). When all three organ systems are involved, the condition is sometimes referred to as "brain-lung-thyroid syndrome." The severity and combination of features can vary considerably, even within the same family. Some individuals have isolated chorea, while others experience the full triad of neurological, thyroid, and pulmonary manifestations. Additional neurological features may include hypotonia, motor delay, dysarthria, ataxia, and in some cases, myoclonus. There is no cure for benign hereditary chorea, and treatment is primarily symptomatic. Levodopa has been reported to improve chorea in some patients, and other medications such as tetrabenazine or methylphenidate have been used with variable success. Thyroid hormone replacement therapy is indicated for those with hypothyroidism, and pulmonary complications are managed supportively. Physical therapy and speech therapy may be beneficial for motor and speech difficulties. Genetic counseling is recommended for affected families. The prognosis is generally favorable, as the chorea tends to stabilize or improve over time and life expectancy is usually normal in the absence of severe pulmonary disease.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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