ZNF91 is an endogenous repressor of the molecular phenotype associated with X-linked dystonia-parkinsonism (XDP).

X-linked dystonia-parkinsonism (XDP) is a severe neurodegenerative disorder resulting from an inherited intronic SINE-Alu-VNTR (SVA) retrotransposon in the TAF1 gene that causes dysregulation of TAF1 transcription. The specific mechanism underlying this dysregulation remains unclear, but it is hypothesized to involve the formation of G-quadruplexes (G4) structures within the XDP-SVA that impede transcription. In this study, we show that ZNF91, a critical repressor of SVA retrotransposons, specifically binds to G4-forming DNA sequences. Further, we found that genetic deletion of ZNF91 exacerbates the molecular phenotype associated with the XDP-SVA insertion in patient cells, while no difference was observed when ZNF91 was deleted from isogenic control cells. Additionally, we observed a significant age-related reduction in ZNF91 expression in whole blood and brain, indicating a progressive loss of repression of the XDP-SVA in XDP. These findings indicate that ZNF91 plays a crucial role in controlling the molecular phenotype associated with XDP. Since ZNF91 binds to G4-forming DNA sequences in SVAs, this suggests that interactions between ZNF91 and G4-forming sequences in the XDP-SVA minimize the severity of the molecular phenotype. Our results showing that ZNF91 expression levels significantly decrease with age provide a potential explanation for the age-related progressive neurodegenerative character of XDP. Collectively, our study provides important insights into the protective role of ZNF91 in XDP pathogenesis and suggests that restoring ZNF91 expression, destabilization of G4s, or targeted repression of the XDP-SVA could be future therapeutic strategies to prevent or treat XDP.

De novo p.Glu61Ter mutation in GCH1 in a Moroccan patient with dopa-responsive dystonia: a case report.

Dopa-responsive dystonia (DRD) is a hereditary movement disorder due to a selective nigrostriatal dopamine deficiency. It is characterized by onset in childhood or adolescence with marked diurnal fluctuation with or without Parkinsonian features, and is caused by mutations in GCH1 gene. We report in this study the clinical and genetic features of the first DRD Moroccan patient. Using a gene panel sequencing, we identified a heterozygous nonsense variant p. Glu61Ter in GCH1. A subsequent targeted segregation analysis by Sanger sequencing validated the presence of the mutation in the patient, which was found to have occurred de novo. The objective of this study is to report the first description of DRD in Morocco, and highlights the importance of new generation sequencing technology in the reduction of medical wandering and the management of hereditary diseases.

Focal dystonia in an adult with L-2- hydroxyglutaric aciduria.

L-2-Hydroxyglutaric aciduria (L-2-HGA) is a rare disorder. The patients have psychomotor retardation, ataxia, macrocephaly, and epilepsy usually in childhood. We present a case of L-2-HGA who developed dystonia in the third decade of life. The family reported symptoms of progressive psychomotor regression since childhood. On assessment, the patient had mild impairment of higher mental functions, mild exotropia, and right-hand dystonia. Brain MRI revealed diffuse bilateral symmetrical subcortical white matter hyperintense signals. 2-hydroxyglutaric acid in urine was elevated and the whole genome sequencing revealed a homogeneous pathogenic variant of the L-2-hydroxyglutarate dehydrogenase (L2HGDH) gene. The prognosis was explained to the caregivers. Patients with mild phenotype L-2-HGA can remain undiagnosed until adulthood. Cases of dystonia even without complaints of epilepsy should be investigated by MRI -brain, urine test and genetic testing to rule out L-2-HGA.

Deep brain stimulation for pediatric pantothenate kinase-associated neurodegeneration with status dystonicus: A case report and literature review.

BACKGROUND: Pantothenate kinase-associated neurodegeneration (PKAN) is a type of inherited metabolic disorder caused by mutation in the PANK2 gene. The metabolic disorder mainly affects the basal ganglia region and eventually manifests as dystonia. For patients of dystonia, their dystonic symptom may progress to life-threatening emergency--status dystonicus. OBJECTIVE: We described a case of a child with PKAN who had developed status dystonicus and was successfully treated with deep brain stimulation (DBS). Based on this rare condition, we analysed the clinical features of PKAN with status dystonicus and reviewed the reasonable management process of this condition. CONCLUSION: This case confirmed the rationality of choosing DBS for the treatment of status dystonicus. Meanwhile, we found that children with classic PKAN have a cluster of risk factors for developing status dystonicus. Once children diagnosed with similar neurodegenerative diseases are under status dystonicus, DBS can be active considered because it has showed high control rate of this emergent condition.

Pyruvate dehydrogenase-E1α deficiency presenting as generalized dystonia: A genetic diagnosis with important clinical implications.

Pyruvate dehydrogenase complex (PDC) deficiency is a genetic mitochondrial disease mostly associated with severe lactic acidosis, rapid progression of neurological symptoms and death during childhood. We present a 33-year-old male with PDC deficiency caused by a Val262Leu mutation in PDHA1gene. He demonstrated generalized dystonia affecting trunk and upper extremities and paraparesis as the most significant features, with onset of symptoms at age 8. Brain MRI showed bilaterally increased signal within the globus pallidus, typical of Leigh syndrome. A periodic lactate increase in serum and cerebrospinal fluid was detected. We describe a case of pyruvate dehydrogenase deficiency being diagnosed only 25 years after the onset of symptoms and highlight PDHC deficiency as a possible cause of treatable dystonia in childhood, which may respond well to thiamine and levodopa treatment.

Genome sequencing reanalysis increases the diagnostic yield in dystonia.

PURPOSE: We investigated the contribution of genomic data reanalysis to the diagnostic yield of dystonia patients who remained undiagnosed after prior genome sequencing. METHODS: Probands with heterogeneous dystonia phenotypes who underwent initial genome sequencing (GS) analysis in 2019 were included in the reanalysis, which was performed through gene-specific discovery collaborations and systematic genomic data reanalysis. RESULTS: Initial GS analysis in 2019 (n = 111) identified a molecular diagnosis in 11.7 % (13/111) of cases. Reanalysis between 2020 and 2023 increased the diagnostic yield by 7.2 % (8/111); 3.6 % (4/111) through focused gene-specific clinical correlation collaborative efforts [VPS16 (two probands), AOPEP and POLG], and 3.6 % (4/111) by systematic reanalysis completed in 2023 [NUS1 (two probands) and DDX3X variants, and a microdeletion encompassing VPS16]. Seven of these patients had a high phenotype-based dystonia score ≥3. Notable unverified findings in four additional cases included suspicious variants of uncertain significance in FBXL4 and EIF2AK2, and potential phenotypic expansion associated with SLC2A1 and TREX1 variants. CONCLUSION: GS data reanalysis increased the diagnostic yield from 11.7 % to 18.9 %, with potential extension up to 22.5 %. While optimal timing for diagnostic reanalysis remains to be determined, this study demonstrates that periodic re-interrogation of dystonia GS datasets can provide additional genetic diagnoses, which may have significant implications for patients and their families.

Expanding the phenotypic and genotypic spectrum of DYT-TUBB4A with seven patients from India.

BACKGROUND: Variants in the TUBB4A gene are associated with dystonia (DYT-TUBB4A), Hypomyelination with Atrophy of the Basal Ganglia and Cerebellum (H-ABC) and spastic paraplegia. Phenotypes intermediate to these three broad phenotypes are also observed. These are rare disorders, and data from diverse populations remains limited. We report seven Indian cases with dystonia phenotype related to TUBB4A mutation. CASES: Among these seven patients, age at onset ranged from 5 to 48 years. Five patients had cranio-cervical onset of dystonia. One patient had prominent parkinsonism with dystonia. Patients responded well to botulinum toxin injected for laryngeal, cervical and jaw dystonia. The patient with parkinsonism responded well to levodopa, albeit with development of dyskinesias. Apart from the common p.Arg2Gly variant in three patients with DYT-TUBB4A, other variants included p.Arg262Pro, p.Arg39Cys and p.Asp245Asn. CONCLUSIONS: We report the first collection of cases with TUBB4A mutation from India. We expand the phenotype to include levodopa-responsive parkinsonism. Indian patients, consistent with global literature, harbor prominent adductor dysphonia, cervical and jaw dystonia, which responds well to botulinum treatment.

[Phenotypic and genotypic spectrum of KMT2B dystonia. Description of three Colombian patients]. / Espectro fenotípico y genotípico de la distonía causada por el gen KMT2B. Descripción de tres casos colombianos.

INTRODUCTION: KMT2B-related dystonia is a childhood-onset movement disorder characterized by focal dystonia of the lower extremities progressing to generalized dystonia with predominant cervical, cranial, and laryngeal involvement. So far, fewer than 100 variants have been reported, the vast majority being de novo mutations. The presenting frame of KMT2B dystonia, with dysmorphology features and other complex neurologic symptoms shows the spectrum of KMT2B dystonia as a probable syndromic disease, rather than an isolated early-onset dystonia, which has been the classic view of the condition. CASE REPORTS: We report three patients who presented regression in their neurodevelopment, focal dystonia of the lower limbs with subsequent generalization, in whom two de novo variants were reported in the KMT2B gene, with a mean age of presentation lower than the average reported worldwide. CONCLUSIONS: We describe the largest local series of patients with KMT2B dystonia in Colombia (to our knowledge), which allows us to expand the genotype-phenotype relationship of this genetic dystonia. Although many affected individuals follow a similar disease course, it is important to determine clinical features that may be associated such as neurodevelopmental regression.

TITLE: Espectro fenotípico y genotípico de la distonía causada por el gen KMT2B. Descripción de tres casos colombianos.Introducción. La distonía relacionada con KMT2B es un trastorno del movimiento hipercinético, de inicio en la infancia, caracterizado inicialmente por distonía focal de las extremidades inferiores que progresa a una distonía generalizada con mayor afectación cervical, craneal y laríngea. Hasta el momento se han descrito aproximadamente 100 variantes causantes de enfermedad, y la mayoría son de novo. La presentación clínica de la distonía con hallazgos fenotípicos comunes en los pacientes, asociada a frecuente afectación del neurodesarrollo, afectación intelectual y otros trastornos del movimiento, hace pensar más en el espectro KMT2B como una condición sindrómica, más que en una distonía aislada de inicio temprano, como clásicamente se ha clasificado. Casos clínicos. Se presenta el caso de tres pacientes con regresión del neurodesarrollo, distonía focal de los miembros inferiores con posterior generalización, en quienes se identificaron tres variantes en el gen KMT2B, en dos de los casos de novo (en una de ellas se desconoce la segregación), y dos de ellas comunicadas por primera vez en la bibliografía. La edad media de presentación fue menor a la edad promedio notificada a nivel mundial. Conclusiones. Describimos una serie de pacientes colombianos con distonía DYT-KMT2B (la más grande en nuestro conocimiento a nivel local), lo que nos permite ampliar la relación genotipo-fenotipo de esta distonía genética. Si bien múltiples individuos afectados siguen un curso de enfermedad similar, es importante determinar las características clínicas que pueden estar asociadas, como la regresión del neurodesarrollo y su potencial clasificación como distonía compleja. Describimos, además, dos nuevas variantes asociadas al fenotipo.

Reduced histone H3K4 trimethylation in oral mucosa of patients with DYT-KMT2B.

BACKGROUND: DYT-KMT2B, also known as DYT28, is a childhood-onset hereditary dystonia caused by KMT2B mutation. The pathogenesis of DYT-KMT2B involves haploinsufficiency of KMT2B, an enzyme that catalyzes specific histone methylation (H3K4me3). Dysmorphic features in patients with DYT-KMT2B suggest that KMT2B dysfunction may extend beyond the neuronal system. Therefore, valuable diagnostic insights may be obtained from readily available tissue samples. OBJECTIVES: To explore the altered H3K4me3 levels in non-neural tissue of DYT-KMT2B patients. METHODS: A database analysis was performed to determine in which parts of the body and in which cells KMT2B is highly expressed. Twelve clinically and genetically diagnosed patients with DYT-KMT2B and 12 control subjects participated in this study. Oral mucosa-derived purified histone proteins were analyzed using Western blotting with anti-H3K4me3 and anti-H4 antibodies. RESULTS: Higher expression of KMT2B was observed in oral keratinocytes and gingival fibroblasts, constituting the oral mucosa. In oral mucosa analyses, DYT-KMT2B cases exhibited markedly reduced H3K4me3 levels compared with the controls. Using a cutoff window of 0.90-0.98, the H3K4me3/H4 expression ratio was able to distinguish patient groups. CONCLUSIONS: Oral mucosa H3K4me3 analysis is currently not sufficient as a diagnostic tool for DYT-KMT2B, but has the advantage for screening test since it is a non-invasive means.

CACNA1A variant associated with generalized dystonia.

INTRODUCTION: CACNA1A gene variants are correlated with different disorders, including episodic ataxia type 2, spinocerebellar ataxia type 6, and familial hemiplegic migraine type 1. Despite dystonia not being a typical manifestation of CACNA1A variants, there are reports indicating a link between this gene mutation and dystonic features. METHODS: We report the case of a patient with a novel missense variant of the CACNA1A gene presenting headache, head and arm tremor, dystonia, episodic painful focal dystonic attacks, and unexplained falls. RESULTS:  A 57-year-old woman presented with a history of neck dystonia, head and arm tremor, and headaches since age 15. In 2017, she progressively developed dystonic tremor of the head and arms with an unremarkable brain MRI. In 2018 she experienced worsening of tremor and developed painful dystonic attacks, resistant to treatments including clonazepam, trihexyphenidyl, baclofen, and levodopa/benserazide. Botulinum toxin injections for neck dystonia provided limited benefit. The next-generation sequencing exam revealed a CACNA1A gene missense variant (NM_023035.2:c.1630C > T; p.Arg544Trp). In 2021 we observed a worsening of dystonia, accompanied by weight loss, mood changes, and unexplained falls. Deep brain stimulation was considered but ruled out due to cortical atrophy and mild cognitive deficits revealed by the neuropsychological examination. DISCUSSION: Only a few studies reported dystonia as part of the clinical features in carriers of CACNA1A mutations. This case points out the relevance of a need to expand the literature on voltage-dependent P/Q-type Ca2 + channels' role in dystonia's pathogenesis and stresses the complex phenotype-genotype presentation of CACNA1A mutation.

Pallidal deep brain stimulation for patients with myoclonus-dystonia without SGCE mutations.

BACKGROUND: Pallidal deep brain stimulation (GPi-DBS) is effective for treating myoclonus and dystonia caused by SGCE mutations (DYT-SGCE, DYT11). However, it is unknown whether GPi-DBS is effective for the treatment of myoclonus-dystonia which is not associated with the SGCE gene mutations. In this study, we investigated the efficacy of GPi-DBS in treating myoclonus-dystonia in SGCE mutation-negative cases. METHODS: Three patients with myoclonus-dystonia without SGCE mutations who underwent GPi-DBS were evaluated preoperatively and 6 months postoperatively using the Unified Myoclonus Rating Scale (UMRS) and Fahn-Marsden Dystonia Rating Scale (FMDRS) for myoclonus and dystonia, respectively. In two of the three patients, myoclonus was more evident during action. Myoclonus was predominant at rest in the other patient, and he was unaware of his dystonia symptoms. The results were compared with those of the four DYT-SGCE cases. RESULTS: The mean UMRS score in patients with myoclonus-dystonia without SGCE mutations improved from 61.7 to 33.7 pre- and postoperatively, respectively, and the mean FMDRS score improved from 7.2 to 4.5. However, the degree of improvement in myoclonus-dystonia in patients without SGCE mutations was inferior to that in patients with DYT-SGCE (the UMRS score improved by 45% and 69%, respectively). CONCLUSIONS: GPi-DBS is effective for treating myoclonus-dystonia in patients with and without SGCE mutations. GPi-DBS should be considered as a treatment option for myoclonus-dystonia without SGCE mutations.

Compound heterozygous mutations in three Chinese patients of Segawa syndrome and their treatment outcomes.

Segawa syndrome is a rare autosomal recessive form of dopa-responsive dystonia resulting from TH gene dysfunction. Patients typically exhibit symptoms such as generalized dystonia, rigidity, tremors, infantile Parkinsonism, and pseudo-spastic paraplegia. Levodopa is often an effective treatment. Due to its rarity, high heterogeneity, and poorly understood pathological mutation and phenotype spectrums, as well as genotype-phenotype and genotype-treatment outcome correlations, Segawa syndrome poses diagnostic and therapeutic challenges. In our study, through clinical and molecular analyses of three Chinese Segawa patients, we re-evaluated the pathogenicity of a TH mutation (c.880G>C;p.G294R) previously categorized as "Conflicting classifications of pathogenicity" in ClinVar. Also, we summarized the clinical phenotypes of all reported Segawa syndrome cases until 2023 and compared them with our patients. We identified a novel phenotype, "cafe-au-lait macules," not previously observed in Segawa patients. Additionally, we discussed the correlation between specific genotypes and phenotypes, as well as genotypes and treatment outcomes of our three cases. Our findings aim to enhance the understanding of Segawa syndrome, contributing to improved diagnosis and treatment approaches in the future.

Stability of Mosaic Divergent Repeat Interruptions in X-Linked Dystonia-Parkinsonism.

BACKGROUND: X-Linked dystonia-parkinsonism (XDP) is an adult-onset neurodegenerative disorder characterized by rapidly progressive dystonia and parkinsonism. Mosaic Divergent Repeat Interruptions affecting motif Length and Sequence (mDRILS) were recently found within the TAF1 SVA repeat tract and were shown to associate with repeat stability and age at onset in XDP, specifically the AGGG [5'-SINE-VNTR-Alu(AGAGGG)2AGGG(AGAGGG)n] mDRILS. OBJECTIVE: This study aimed to investigate the stability of mDRILS frequencies and stability of (AGAGGG)n repeat length during transmission in parent-offspring pairs. METHODS: Fifty-six families (n = 130) were investigated for generational transmission of repeat length and mDRILS. The mDRILS stability of 16 individuals was assessed at two sampling points 1 year apart. DNA was sequenced with long-read technologies after long-range polymerase chain reaction amplification of the TAF1 SVA. Repeat number and mDRILS were detected with Noise-Cancelling Repeat Finder (NCRF). RESULTS: When comparing the repeat domain, 51 of 65 children had either contractions or expansions of the repeat length. The AGGG frequency remained stable across generations at 0.074 (IQR: 0.069-0.078) (z = -0.526; P = 0.599). However, the median AGGG frequency in children with an expansion (0.072 [IQR: 0.066-0.076]) was lower compared with children with retention or contraction (0.080 [IQR: 0.073-0.083]) (z = -0.007; P = 0.003). In a logistic regression model, the AGGG frequency predicted the outcome of either expansion or retention/contraction when including repeat number and sex as covariates (ß = 80.7; z-score = 2.63; P = 0.0085). The AGGG frequency varied slightly over 1 year (0.070 [IQR: 0.063-0.080] to 0.073 [IQR: 0.069-0.078]). CONCLUSIONS: Our results show that a higher AGGG frequency may stabilize repeats across generations. This highlights the importance of further investigating mDRILS as a disease-modifying factor with generational differences. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Genetic analysis of IRF2BPL in a Taiwanese dystonia cohort: The genotype and phenotype correlation.

OBJECTIVE: IRF2BPL mutation has been associated with a rare neurodevelopmental disorder with abnormal movements, including dystonia. However, the role of IRF2BPL in dystonia remains elusive. We aimed to investigate IRF2BPL mutations in a Taiwanese dystonia cohort. METHODS: A total of 300 unrelated patients with molecularly unassigned isolated (n = 256) or combined dystonia (n = 44) were enrolled between January 2015 and July 2023. The IRF2BPL variants were analyzed based on whole exome sequencing. The in silico prediction of the identified potential pathogenic variant was performed to predict its pathogenicity. We also compared the clinical and genetic features to previous literature reports. RESULTS: We identified one adolescent patient carrying a de novo heterozygous pathogenic variant of IRF2BPL, c.379C>T (p.Gln127Ter), who presented with generalized dystonia, developmental regression, and epilepsy (0.33% of our dystonia cohort). This variant resides within the polyglutamine (poly Q) domain before the first PEST sequence block of the IRF2BPL protein, remarkably truncating the protein structure. Combined with other patients with IRF2BPL mutations in the literature (n = 60), patients with variants in the poly Q domain have a higher rate of nonsense mutations (p < 0.001) and epilepsy (p = 0.008) than patients with variants in other domains. Furthermore, as our index patient, carriers with substitutions before the first PEST sequence block have significantly older age of onset (p < 0.01) and higher non-epilepsy symptoms, including generalized dystonia (p = 0.003), and ataxia (p = 0.003). INTERPRETATION: IRF2BPL mutation is a rare cause of dystonia in our population. Mutations in different domains of IRF2BPL exhibit different phenotypes.

Dopa-responsive dystonia and paroxysmal dystonic attacks associated with ATP1A3 gene variant.

An 18-year-old man had episodes of severe generalised dystonia, from aged 7 months and becoming progressively more frequent. He also had gradually developed interictal limb dystonia. He was initially diagnosed with paroxysmal kinesigenic dyskinesia but he did not improve with several medications. A levodopa trial led to levodopa-induced dyskinetic movements. However, a lower titration of 25 mg of levodopa two times per day substantially improved his motor features and quality of life. Laboratory investigations and MR scans of the brain were unremarkable. Whole-exome sequencing identified a pathogenic variant in the ATP1A3 gene. The ATP1A3-spectrum disorders include non-classical phenotypes such as paroxysmal dystonic attacks. A response to dopamine response is unusual in these disorders. This case highlights the importance of levodopa trials in early-onset dystonia cases.

CHD8-related disorders redefined: an expanding spectrum of dystonic phenotypes.

BACKGROUND: Heterozygous loss-of-function variants in CHD8 have been associated with a syndromic neurodevelopmental-disease spectrum, collectively referred to as CHD8-related neurodevelopmental disorders. Several different clinical manifestations, affecting neurodevelopmental and systemic domains, have been described, presenting with highly variable expressivity. Some expressions are well established and comprise autism spectrum disorders, psychomotor delay with cognitive impairment, postnatal overgrowth with macrocephaly, structural brain abnormalities, gastrointestinal disturbances, and behavioral and sleep-pattern problems. However, the complete phenotypic spectrum of CHD8-related disorders is still undefined. In 2021, our group described two singular female patients with CHD8-related neurodevelopmental disorder and striking dystonic manifestations, prompting the suggestion that dystonia should be considered a possible component of this condition. CASE SERIES PRESENTATION: We describe three additional unrelated female individuals, each carrying a different CHD8 frameshift variant and whose clinical presentations were primarily characterized by young-onset dystonia. Their dystonic manifestations were remarkably heterogeneous and ranged from focal, exercise-dependent, apparently isolated forms to generalized permanent phenotypes accompanied by spasticity and tremor. Neurocognitive impairment and autistic behaviors, typical of CHD8-related disorders, were virtually absent or at the mild end of the spectrum. CONCLUSIONS: This work validates our previous observation that dystonia is part of the phenotypic spectrum of CHD8-related neurodevelopmental disorders with potential female preponderance, raising new challenges and opportunities in the diagnosis and management of this condition. It also highlights the importance of in-depth neurologic phenotyping of patients carrying variants associated with neurodevelopmental disorders, as the connection between neurodevelopmental and movement disorders is proving closer than previously appreciated.