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

Systematic review of thyroid function in NKX2-1-related disorders: Screening and diagnosis

BACKGROUND

NKX2-1-related disorders (NKX2-1-RD) are rare conditions affecting lung, thyroid, and brain development, primarily caused by pathogenic variants or deletions in the NKX2-1 gene. Congenital hypothyroidism (CH) is a common endocrine manifestation, leading to irreversible intellectual disability if left untreated.

OBJECTIVES

The aim was to evaluate the current evidence for the use of screening and diagnostic techniques for endocrine alterations in patients with NKX2-1-RD.

METHODS

This systematic review was reported following the PRISMA guidelines. Two separate research questions in PICO format were addressed to cover initial screening and diagnosis procedures for endocrine diseases in patients with NKX2-1-RD. Eligibility criteria focused on patients with genetic confirmation of the disease and hypothyroidism. Various databases were searched, and data were extracted and assessed independently by two reviewers.

RESULTS

Out of 1012 potentially relevant studies, 46 were included, for a total of 113 patients. CH was the most frequent endocrine alteration (45% of patients). Neonatal screening was reported in only 21% of patients based on blood TSH measurements. TSH thresholds varied widely across studies, making hypothyroidism detection ranges difficult to establish. Diagnostic tests using serum TSH were used to diagnose hypothyroidism or confirm its presence. 35% of patients were diagnosed at neonatal age, and 42% at adult age. Other hormonal dysfunctions identified due to clinical signs, such as anterior pituitary deficiencies, were detected later in life. Thyroid scintigraphy and ultrasonography allowed for the description of the thyroid gland in 30% of cases of hypothyroidism. Phenotypic variability was observed in individuals with the same variants, making genotype-phenotype correlations challenging.

CONCLUSION

This review highlights the need for standardized protocols in endocrine screening for NKX2-1-RD, emphasizing the importance of consistent methodology and hormone threshold levels. Variability in NKX2-1 gene variants further complicates diagnostic efforts. Future research should concentrate on optimizing early screening protocols and diagnostic strategies.

Systematic review of drug therapy for chorea in NXK2-1-related disorders: Efficacy and safety evidence from case studies and series

BACKGROUND

The NKX2-1-related disorders (NKX2-1-RD) is a rare disorder characterized by choreiform movements along with respiratory and endocrine abnormalities. The European Reference Network of Rare Neurological Disorders funded by the European Commission conducted a systematic review to assess drug treatment of chorea in NKX2-1-RD, aiming to provide clinical recommendations for its management.

METHODS

A systematic pairwise review using various databases, including MEDLINE, Embase, Cochrane, CINAHL, and PsycInfo, was conducted. The review included patients diagnosed with chorea and NKX2-1-RD genetic diagnosis, drug therapy as intervention, no comparator, and outcomes of chorea improvement and adverse events. The methodological quality of the studies was assessed, and the study protocol was registered in PROSPERO.

RESULTS

Of the 1417 studies examined, 28 studies met the selection criteria, consisting of 68 patients. The studies reported 22 different treatments for chorea, including carbidopa/levodopa, tetrabenazine, clonazepam, methylphenidate, carbamazepine, topiramate, trihexyphenidyl, haloperidol, propranolol, risperidone, and valproate. No clinical improvements were observed with carbidopa/levodopa, tetrabenazine, or clonazepam, and various adverse effects were reported. However, most patients treated with methylphenidate experienced improvements in chorea and reported only a few negative effects. The quality of evidence was determined to be low.

CONCLUSIONS

The management of chorea in individuals with NKX2-1-RD presents significant heterogeneity and lack of clarity. While the available evidence suggests that methylphenidate may be effective in improving chorea symptoms, the findings should be interpreted with caution due to the limitations of the studies reviewed. Nonetheless, more rigorous and comprehensive studies are necessary to provide sufficient evidence for clinical recommendations.

Chorea: An unusual manifestation of endocrine diseases

Chorea is a movement disorder involving involuntary movements of muscles of the face, neck, and limbs, usually caused by basal ganglia lesions. As an important part of the presentation of many neurological diseases, chorea is also an unusual manifestation of endocrine diseases and can be challenging to diagnose. Although the most common etiology of chorea is genetic, it is vital to identify acquired or symptomatic chorea, as these are potentially treatable conditions. This review summarizes the latest developments in various endocrine disease-related chorea, which will help clinicians to correctly identify and accurately treat it.

Nonsense Mutations in Eukaryotes

Nonsense mutations are a type of mutations which results in a premature termination codon occurrence. In general, these mutations have been considered to be among the most harmful ones which lead to premature protein translation termination and result in shortened nonfunctional polypeptide. However, there is evidence that not all nonsense mutations are harmful as well as some molecular mechanisms exist which allow to avoid pathogenic effects of these mutations. This review addresses relevant information on nonsense mutations in eukaryotic genomes, characteristics of these mutations, and different molecular mechanisms preventing or mitigating harmful effects thereof.

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.

Levodopa-Responsive Chorea: A Review

Background:

Chorea is one of the disabling movement disorders, and the number of drugs which can treat this disorder effectively is limited. Tetrabenazine and deutetrabenazine are the two drugs approved by the US-FDA for the treatment of chorea associated with HD. Levodopa can improve chorea in some disorders, and this review aims to provide information on the use of levodopa in chorea.

Methods:

A literature search was performed in February 2019 using the following terms “levodopa chorea,” “levodopa TITF-1,” levodopa brain-lung-thyroid syndrome,” and “levodopa Huntington's Disease.” The information regarding the etiology, outcome, and dose of levodopa was collected.

Results:

We found a total of 18 cases in the literature where the benefit was reported with levodopa. Majority of the cases were brain-thyroid-lung (BTL) syndrome (50%). Another 5 cases were HD (Huntington's Disease), one with PCH type 2 (Pontocerebellar hypoplasia type 2), one with meningovascular syphilis, and two patients with Sydenham chorea. The patients with BTL syndrome responded to a very low dose of levodopa.

Discussion:

This review suggests that levodopa has the potential to improve chorea in BTL syndrome while its use in chorea due to other disorders requires further study. BTL syndrome due to NKX2-1 mutation responded to levodopa while we did not find any case of chorea due to ADCY-5 mutation responding to levodopa.

Is Benign Hereditary Chorea Really Benign? Brain-Lung-Thyroid Syndrome Caused by NKX2-1 Mutations

BACKGROUND

Since its localization to the NKX2-1 gene in 2002, the phenotype of the disorder historically called "benign hereditary chorea" has been expanding beyond chorea.

METHODS

The phenomenology of movement disorders and other symptomatology associated with mutations in NKX2-1 were characterized after a detailed evaluation of consecutive patients evaluated in our clinic over the past 3 years.

RESULTS

We studied 5 patients (3 females), ages 2 to 31 years, with confirmed pathogenic variants in NKX2-1. All patients exhibited chorea, gross motor delay, and gait impairment. Other symptoms included neonatal respiratory failure (n = 4), cognitive deficits (n = 3), hypothyroidism (n = 4), joint laxity (n = 2), myoclonus (n = 1), hypotonia (n = 3), and seizures (n = 1). Chorea often proved refractory to medical therapies.

CONCLUSIONS

The phenotype associated with pathogenic variants in NKX2-1 frequently includes disabling and often medically refractory neurological and non-neurological abnormalities. We therefore suggest that the term benign hereditary chorea be abandoned in favor of its genetic designation as NKX2-1-related disorder.

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.

NKX2.1-Related Disorders: a novel mutation with mild clinical presentation

Background

A highly variable phenotype characterized by thyroid, respiratory and neurological defects has been reported in an already established group of disorders namely NKX2.1-related disorders. We describe here the case of an infant with a novel mutation of the NKX2.1 gene characterized by mild clinical presentation.

Aim of the study was to elucidate the genotype-phenotype correlation in our patient.

Methods

We performed genetic analysis of the NKX2.1 gene in an infant with no neonatal respiratory distress and near-normal results at neonatal screening test for congenital hypothyroidism, choreoathetosis, ataxia and delayed independent walking.

Results

A novel mutation of the NKX2.1 gene has been identified, that is responsible for a mild framework of congenital hypothyroidism and neurological symptoms.

Conclusions

The frequency of congenital hypothyroidism cases associated with NKX2.1 mutations is expected to be higher in a subgroup of patients, selected according to the neurological presentation. In these patients the analysis of NKX2.1 mutational status is recommended.

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.

Benign hereditary chorea related to NKX2.1: expansion of the genotypic and phenotypic spectrum

AIM

Benign hereditary chorea is a dominantly inherited, childhood-onset hyperkinetic movement disorder characterized by non-progressive chorea and variable degrees of thyroid and respiratory involvement. Loss-of-function mutations in NKX2.1, a gene vital to the normal development and function of the brain, lungs, and thyroid, have been identified in a number of individuals.

METHOD

Clinical data from individuals with benign hereditary chorea identified through paediatric neurology services were collected in a standardized format. The NKX2.1 gene was analysed by Sanger sequencing, multiplex ligation-dependent probe amplification, and microarray analysis.

RESULTS

Six of our cohort were female and four male, median age at assessment was 8 years 6 months (range 1 y 6 mo-18 y). We identified 10 probands with NKX2.1 mutations; nine of these mutations are novel (including two whole-gene deletions) and one has been previously reported. Of the 10 individuals, eight presented with muscle hypotonia and four had evidence of hypothyroidism or respiratory involvement. Only three out of the 10 individuals had the full triad of 'brain-lung-thyroid syndrome' symptoms. Additional clinical characteristics occurring in individual participants included growth hormone deficiency, pes cavus, kyphosis, duplex kidney, and obsessive-compulsive disorder.

INTERPRETATION

Our data suggest that the neurological phenotype is prominent in this condition and that many patients with benign hereditary chorea do not have the classic triad of brain-lung-thyroid syndrome. The extended phenotype may include obsessive-compulsive disorder and skeletal abnormalities.

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 [(11)C]-CFT for the presynaptic dopamine transporter function and [(11)C]-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.