Benign hereditary chorea: dopaminergic brain imaging in patients with a novel intronic NKX2.1 gene mutation
Mutations in the NKX2.1 gene, which is essential for the development, differentiation and organization of the basal ganglia, cause benign hereditary chorea (BHC) characterized by childhood-onset non-progressive chorea. We herein report the clinical features of six patients from a single family with a novel intronic mutation and present the dopaminergic neuronal imaging by using positron emission tomography (PET) imaging to assess the integrity of the striatal dopaminergic system using [11C]-CFT for the presynaptic dopamine transporter function and [11C]-raclopride for the postsynaptic D2 receptor function. The patients showed mild generalized chorea without either congenital hypothyroidism or a history of pulmonary infection and some of the patients had goiter. Genetic analyses of NKX2.1 gene showed a novel heterozygous c.464-9C>A mutation that created a new acceptor splice site resulting in the production of an aberrant transcript with a 7-bp insertion identical to a intronic sequence of genomic DNA. Oral levodopa failed to improve the involuntary movement, while haloperidol, a dopamine D2 receptor blocking agent, exacerbated the choric movement in a single patient. The dopaminergic PET studies in the two patients revealed decreased raclopride binding in the striatum, while the CFT binding was not altered. The impairment of D2 receptor function in the basal ganglia may result in exacerbation of the chorea induced by haloperidol. The molecular brain imaging and therapeutic response may help elucidate the pathophysiological mechanism of the motor control in the BHC-associated NKX2.1 mutation.
KeywordsBenign hereditary chorea PET Levodopa Dopamine Mutation NKX2.1 TITF-1
No commercial support was provided for this study. This study was not sponsored by any outside organization. All of the authors indicate that they have no financial relationships to report.
Conflicts of interest
All authors report no disclosures of financial relationships.
All human studies have been approved by the appropriate ethics committee and have therefore been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki.
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