Benign hereditary chorea: clinical, neuroimaging, and genetic findings

Altered pituitary morphology as a sign of benign hereditary chorea caused by TITF1/NKX2.1 mutations

Benign hereditary chorea (BHC) is a rare genetically heterogeneous movement disorder, in which conventional neuroimaging has been reported as normal in most cases. Cystic pituitary abnormalities and features of empty sella have been described in only 7 patients with BHC to date. We present 4 patients from 2 families with a BHC phenotype, 3 of whom underwent targeted pituitary MR imaging and genetic testing. All four patients in the two families displayed a classic BHC phenotype. The targeted pituitary MR imaging demonstrated abnormal pituitary sella morphology. Genetic testing was performed in three patients, and showed mutations causing BHC in three of the patients, as well as identifying a novel nonsense mutation of the TITF1/NKX2-1 gene in one of the patients. The presence of the abnormal pituitary sella in two affected members of the same family supports the hypothesis that this sign is a distinct feature of the BHC phenotype spectrum due to mutations in the TITF1 gene. Interestingly, these abnormalities seem to develop in adult life and are progressive. They occur in at least 26% of patients affected with Brain-lung-thyroid syndrome. As a part of the management of these patients we recommend to perform follow-up MRI brain with dedicated pituitary imaging also in adult life as the abnormality can occur years after the onset of chorea.

Recurrent drop attacks in early childhood as presenting symptom of benign hereditary chorea caused by TITF1 gene mutations

Drop attacks are sudden, spontaneous falls without loss of consciousness, followed by rapid recovery. Causes in children include severe epilepsies, movement disorders, cataplexy, and psychiatric disorders. We describe two children (a 3-year-old female and a 12-year-old male) with mild neuromotor delay and sudden falls appearing upon starting to walk. Extensive clinical and laboratory investigation was unremarkable. Twenty to 22 months after the onset of falls, both children developed subtle choreiform movements, affecting all four limbs, leading to frequent falls, at times causing traumatic injury. A heterozygous mutation of the TITF1/NKX2-1 gene (14q13) was detected in both patients, allowing the diagnosis of benign hereditary chorea (BHC). Treatment with levodopa attenuated abnormal movements and led to disappearance of drop attacks. A diagnosis of BHC should be considered in young children with recurrent and unexplained drop attacks, especially if associated with neuromotor delay, even in the absence of choreiform movements.

Benign Hereditary Chorea: An Update

Benign hereditary chorea (BHC) is a childhood-onset, hyperkinetic movement disorder normally with little progression of motor symptoms into adult life. The disorder is caused by mutations to the NKX2.1 (TITF1) gene and also forms part of the “brain–lung–thyroid syndrome”, in which additional developmental abnormalities of lung and thyroid tissue are observed. In this review, we summarize the main clinical findings in “classical” BHC syndrome and discuss more recently reported atypical features, including non-choreiform movement phenotypes. We highlight additional non-motor characteristics such as cognitive impairment and psychiatric symptoms, while discussing the evidence for BHC as a developmental disorder involving impaired neural migration and other multisystem developmental abnormalities. Finally, we will discuss the efficacy of available therapies in both affected pediatric and adult cohorts. Delineation of the BHC disease spectrum will no doubt expand our understanding of this disorder, facilitating better targeting of genetic testing and establish a framework for future clinical trials.

A novel de novo mutation of the TITF1/NKX2-1 gene causing ataxia, benign hereditary chorea, hypothyroidism and a pituitary mass in a UK family and review of the literature

Benign hereditary chorea (BHC) is a rare autosomal dominant condition characterized by early onset, non-progressive chorea, usually caused by mutations in the thyroid transcription factor-1 gene (TITF1). We describe a novel mutation arising de novo in a proband presenting in infancy with delayed walking and ataxia. She later developed chorea, then hypothyroidism and a large cystic pituitary mass. Her daughter presented in infancy with delayed walking and ataxia and went on to develop non-progressive chorea and a hormonally inactive cystic pituitary mass. Mutational analysis of the whole coding region of the TITF1 gene was undertaken and compared with a population study of 160 control subjects. This showed that both affected subjects have a heterozygous A > T substitution at nucleotide 727 of the TITF1 gene changing lysine to a stop codon at residue 211. Genetic analysis of parents and siblings of the proband confirmed that the mutation arose de novo in the proband. The mutated lysine is an evolutionarily highly conserved amino acid in the protein homoeodomain (HD) where most point mutations associated with BHC are located. The range of mutations in BHC is reviewed with particular emphasis on pituitary abnormalities. Cystic pituitary masses and abnormalities of the sella turcica are reported in just 6.4 % of published cases. This is a new nonsense mutation associated with ataxia, benign chorea and pituitary abnormalities which further extends the phenotype of this condition. Mutational screening of TITF1 is important in cases of sporadic or dominant juvenile-onset ataxia, with mild chorea where no other cause is found, particularly if pituitary abnormalities are seen on imaging.

Genetic disorders of thyroid metabolism and brain development

Normal thyroid metabolism is essential for human development, including the formation and functioning of the central and peripheral nervous system. Disorders of thyroid metabolism are increasingly recognized within the spectrum of paediatric neurological disorders. Both hypothyroid and hyperthyroid disease states (resulting from genetic and acquired aetiologies) can lead to characteristic neurological syndromes, with cognitive delay, extrapyramidal movement disorders, neuropsychiatric symptoms, and neuromuscular manifestations. In this review, the neurological manifestations of genetic disorders of thyroid metabolism are outlined, with particular focus on Allan-Herndon-Dudley syndrome and benign hereditary chorea. We report in detail the clinical features, major neurological and neuropsychiatric manifestations, molecular genetic findings, disease mechanisms, and therapeutic strategies for these emerging genetic 'brain-thyroid' disorders.

Genetics of Huntington's disease and related disorders

Huntington's disease is the most frequent form of the hereditary choreas and has a multifaceted phenotype including cognitive and psychiatric impairment. The disorder is due to a dynamic mutation, which also influences the onset age of the disorder. Other genetic modifiers of the HD phenotypes have been suggested but often not confirmed by independent studies. Several syndromes with similar presentation have different genetic backgrounds, including the neuroacanthocytoses, mainly choreoacanthocytosis and MacLeod syndrome as a result of mutations in chorein and Kell protein, respectively, but also benign hereditary chorea, owing to mutations in NKX-2-1, and paroxysmal kinesigenic dyskinesia, as a result of recently found mutations in the proline-rich transmembrane protein 2, PRRT2. Chorea can also be a major feature in other neurogenetic disorders, including the spinocerebellar ataxias and also in neurometabolic disorders.

Huntington's disease and Huntington's disease-like syndromes: an overview

PURPOSE OF REVIEW

The differential diagnosis of chorea syndromes may be complex and includes various genetic disorders such as Huntington's disease and mimicking disorders called Huntington's disease-like (HDL) phenotypes. To familiarize clinicians with these (in some cases very rare) conditions we will summarize the main characteristics.

RECENT FINDINGS

HDL disorders are rare and account for about 1% of cases presenting with a Huntington's disease phenotype. They share overlapping clinical features, so making the diagnosis purely on clinical grounds may be challenging, however presence of certain characteristics may be a clue (e.g. prominent orofacial involvement in neuroferritinopathy etc.), Information of ethnic descent will also guide genetic work-up [HDL2 in Black Africans; dentatorubral-pallidoluysian atrophy (DRPLA) in Japanese etc.], Huntington's disease, the classical HDL disorders (except HDL3) and DRPLA are repeat disorders with anticipation effect and age-dependent phenotype in some, but genetic underpinnings may be more complicated in the other chorea syndromes.

SUMMARY

With advances in genetics more and more rare diseases are disentangled, allowing molecular diagnoses in a growing number of choreic patients. Hopefully, with better understanding of their pathophysiology we are moving towards mechanistic therapies.

TITF-1 gene mutation in a case of sporadic non-progressive chorea. Response to levodopa treatment

Benign hereditary chorea (BHC) is a rare autosomal dominant disorder characterized by non-progressive chorea of early onset, without other underlying progressive neurologic dysfunction. Hypothyroidism and pulmonary problems may also be associated. Recently, mutations in the thyroid transcription factor 1 gene (TITF-1), linked to chromosome 14q, have been related to this disorder. We describe the clinical phenotype and response to levodopa treatment in a 6 year-old girl affected with sporadic non-progressive chorea, and a de novo TITF-1 gene mutation, in order to increase understanding of this rare and misdiagnosed disorder.

Update on the Non-Huntington's Disease Choreas with Comments on the Current Nomenclature

CHOREA CAN BE CAUSED BY A MULTITUDE OF ETIOLOGIES: neurodegenerative, pharmacological, structural, metabolic, and others. In absence of other apparent causes, exclusion of Huntington's disease is often a first step in the diagnostic process. There are a number of neurodegenerative disorders whose genetic etiology has been identified in the past decade. Molecular diagnosis has enabled genetic identification of disorder subtypes which were previously grouped together, such as the neurodegeneration with brain iron accumulation disorders and the neuroacanthocytosis syndromes, as well as identification of phenotypic outliers for recognized disorders. Correct molecular diagnosis is essential for genetic counseling and, hopefully, ultimately genetic therapies. In addition, there has recently been recognition of other disorders which can mimic neurodegenerative disorders, including paraneoplastic and prion disorders. This article focuses upon recent developments in the field but is not intended to provide an exhaustive review of all causes of chorea, which is available elsewhere. I also discuss the nomenclature of these disorders which has become somewhat unwieldy, but may ultimately be refined by association with the causative gene.

Hypoperfusion in caudate nuclei in patients with brain-lung-thyroid syndrome

Mutations in NKX2-1 cause neurological, pulmonary, and thyroid hormone impairment. Recently, the disease was named brain-lung-thyroid syndrome. Here, we report three patients with brain-lung-thyroid syndrome. All patients were unable to walk until 24 months of age, and still have a staggering gait, without mental retardation. They have also had choreoathetosis since early infancy. Genetic analysis of NKX2-1 revealed a novel missense mutation (p.Val205Phe) in two patients who were cousins and their maternal families, and a novel 2.6-Mb deletion including NKX2-1 on chromosome 14 in the other patient. Congenital hypothyroidism was not detected on neonatal screening in the patient with the missense mutation, and frequent respiratory infections were observed in the patient with the deletion in NKX2-1. Oral levodopa did not improve the gait disturbance or involuntary movement. The results of (99m)Tc-ECD single-photon emission computed tomography (ECD-SPECT) analyzed using the easy Z-score imaging system showed decreased cerebral blood flow in the bilateral basal ganglia, especially in the caudate nuclei, in all three patients, but no brain magnetic resonance imaging (MRI) abnormalities. These brain nuclear image findings indicate that NKX2-1 haploinsufficiency causes dysfunction of the basal ganglia, especially the caudate nuclei, resulting in choreoathetosis and gait disturbance in this disease.

Differential diagnosis of chorea

Chorea is a common movement disorder that can be caused by a large variety of structural, neurochemical (including pharmacologic), or metabolic disturbances to basal ganglia function, indicating the vulnerability of this brain region. The diagnosis is rarely indicated by the simple phenotypic appearance of chorea, and can be challenging, with many patients remaining undiagnosed. Clues to diagnosis may be found in the patient's family or medical history, on neurologic examination, or upon laboratory testing and neuroimaging. Increasingly, advances in genetic medicine are identifying new disorders and expanding the phenotype of recognized conditions. Although most therapies at present are supportive, correct diagnosis is essential for appropriate genetic counseling, and ultimately, for future molecular therapies.

A novel nonsense mutation in the TITF-1 gene in a Japanese family with benign hereditary chorea

A Japanese family with a novel nonsense mutation in the TITF-1 gene (p.Y98X) is described. The proband showed severe generalized chorea, delayed motor development, subnormal intelligence, congenital hypothyroidism, bronchial asthma, and a history of pulmonary infection, all of which are characteristic features of Brain-Thyroid-Lung syndrome. On the other hand, her brother and mother showed a mild benign hereditary chorea (BHC) phenotype with congenital hypothyroidism. Intrafamilial phenotypic variation is common in BHC/Brain-Thyroid-Lung syndrome and suggests the existence of other genetic or environmental factors regulating TITF-1 function. Although choreic movement in BHC/Brain-Thyroid-Lung syndrome is recognized as non-progressive, the proband showed re-exacerbation of choreic movement at puberty. The dopamine agonist, ropinirole hydrochloride, reduced her choreic movements, suggesting that levodopa and/or dopamine agonists may compensate for underdeveloped dopaminergic pathways in this disorder.

Benign hereditary chorea: an update

Benign hereditary chorea (BHC, MIM 118700) is a rare autosomal dominant disorder manifesting with chorea in conjunction with hypothyroidism and respiratory problems, a triad also named "brain-lung-thyroid syndrome". BHC is characterized by childhood onset with minimal or no progression into adult life and normal cognitive function. The genetic basis of BHC has been partially resolved, when mutations in the TTF1 gene on chromosome 14q13 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 (also known as TITF1, TEBP or NKX2-1), belonging to the NKX2 homeodomain transcription factor family, has been implicated in several important molecular pathways essential for brain, thyroid and lung morphogenesis. Clinical evaluation of TTF1 gene mutations carrier patients exposed the involvement of each of the triad's components characterized by heterogeneity between index cases and even within families. This review highlights the current updates on expanded clinical aspects of BHC, imaging and treatment experience, its genetic markers, proposed molecular mechanisms, animal models and link to cancer.

Benign hereditary chorea

Benign hereditary chorea (BHC) is a hyperkinetic movement disorder that historically has been characterized as a nonprogressive, dominantly inherited, childhood-onset chorea with normal intelligence. However, in some cases, atypical features were described such that controversy arose regarding whether BHC was a single syndrome. In 2002, a candidate gene, thyroid transcription factor (TITF-1), was identified to cause at least some cases of BHC. Since that time, the classical phenotype has expanded further to include "brain-thyroid-lung syndrome," which, in addition to the neurological symptoms, also manifests variable degrees of thyroid and lung abnormalities. Pathophysiologic mechanisms by which symptoms can occur are postulated to include haploinsufficiency (loss of function) and/or dominant negative effect on wild-type protein. However, genotype-phenotype correlations are complex and there is no clear relationship between mutation size, location or type of mutation, and severity of phenotype. Gross and microscopic pathology has been unremarkable, though immunohistochemistry suggests that BHC may manifest as a result of a reduced complement of migratory interneurons to the striatum and cortex. This chapter reviews the historical literature and current understanding regarding this familial, developmental disorder.

Acute and chronic chorea in childhood

This review discusses diagnostic evaluation and management of chorea in childhood. Chorea is an involuntary, hyperkinetic movement disorder characterized by continuous, jerky, or flowing movement fragments, with irregular timing and direction. It tends to be enhanced by voluntary actions and generally causes interference with fine motor function. The diagnostic evaluation begins with accurate classification of the movement disorder followed by consideration of the time course. Most previously healthy children presenting with acute/subacute chorea have an autoimmune etiology. Chronic chorea usually occurs as part of encephalopathies or diseases causing more global neurologic symptoms. We review the management of acute/subacute and chronic choreas, with special emphasis on Sydenham chorea and benign hereditary chorea.