Fahr's disease linked to a novel mutation in MYORG variants manifesting as paroxysmal limb stiffness and dysarthria: Case report and literature review.

BACKGROUND: Primary familial brain calcification (PFBC) is a rare hereditary neurodegenerative disorder associated with the MYORG gene; however, the clinical and radiological characteristics of MYORG-PFBC remain unclear. METHODS: We present relevant medical data obtained from a patient affected by PFBC with a novel MYORG variant and conducted a mutational analysis of MYORG in her family members. We reviewed all reported PFBC cases with biallelic MYORG mutations until April 1, 2023, and summarized the associated clinical and radiological features and mutation sites. RESULTS: The patient (22-year-old woman) exhibited paroxysmal limb stiffness and dysarthria for 3 years. Computed tomography revealed calcifications in the paraventricular white matter, basal ganglia, thalamus, and cerebellum. Whole-exome sequencing revealed a novel homozygous frameshift variant (c.743delG: p.G248Afs*32) in exon 2 of the MYORG gene (NM_020702.5). To date, 62 families and 64 mutation sites have been reported. Among the reported biallelic MYORG mutations, 57% were homozygous and 43% were compound heterozygous. Individuals with biallelic MYORG mutations experience more severe brain calcification with approximately 100% clinical penetrance. Ten single heterozygous mutation sites are associated with significant brain calcifications. CONCLUSION: All patients with primary brain calcification, particularly younger patients without a family history of the disease, should be screened for MYORG mutations.

Clinical Reasoning: A 50-Year-Old Man With Progressive Limb Weakness and Slurred Speech.

A 50-year-old man presented with a 9-month history of progressive left arm weakness and dysarthria. Family history showed that his parents are cousins, and one of his siblings died of motor neuron disease. Brain MRI showed T2-weighted white matter hyperintensities along the course of pyramidal tracts. Neurologic examination and EMG revealed upper and lower motor neuron signs involving the bulbar, cervical, thoracic, and lumbosacral segments, which meets the criteria of a definite amyotrophic lateral sclerosis (ALS), according to the revised EI Escorial criteria. Whole-exome genetic sequencing found 2 novel LYST missense variations, confirming the diagnosis of Chediak-Higashi syndrome (CHS), a rare autosomal recessive hematologic disorder. Our case indicates that CHS can present as ALS phenotype, and the LYST might be a novel causative gene for ALS.

Clinical and Molecular Features of POLG-Related Sensory Ataxic Neuropathy with Dysarthria and Ophthalmoparesis.

Sensory ataxic neuropathy, dysarthria, and ophthalmoparesis (SANDO) is a rare mitochondrial disorder associated with mutations in the POLG gene, which encodes the DNA polymerase gamma catalytic subunit. A few POLG-related SANDO cases have been reported, but the genotype-phenotype correlation remains unclear. Here, we report a patient with SANDO carrying two novel missense variants (c.2543G>C, p.G848A and c.452 T>C, p.L151P) in POLG. We also reviewed previously reported cases to systematically evaluate the clinical and genetic features of POLG-related SANDO. A total of 35 distinct variants in the coding region of POLG were identified in 63 patients with SANDO. The most frequent variant was the p.A467T variant, followed by the p.W748S variant. The clinical spectrum of SANDO is heterogeneous. No clear correlation has been observed between the mutation types and clinical phenotypes. Our findings expand the mutational spectrum of POLG and contribute to clinical management and genetic counseling for POLG-related SANDO.

Auditory-perceptual voice and speech evaluation in ATP1A3 positive patients.

INTRODUCTION: Bulbar symptoms are frequent in patients with rapid-onset dystonia-parkinsonism (RDP). RDP is caused by ATP1A3 mutations, with onset typically within 30 days of stressor exposure. Most patients have impairments in speech (dysarthria) and voice (dysphonia). These have not been quantified. We aimed to formally characterize these in RDP subjects as compared to mutation negative family controls. METHODS: We analyzed recordings in 32 RDP subjects (male = 21, female = 11) and 29 mutation negative controls (male = 15, female = 14). Three raters, blinded to mutation status, rated speech and vocal quality. Dysarthria was classified by subtype. Dysphonia was rated via the GRBAS (Grade, Roughness, Breathiness, Asthenia, Strain) scale. We used general neurological exams and the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) to assess dysarthria, dystonia, and speech/swallowing dysfunction. RESULTS: The presence of dysarthria was more frequent in RDP subjects compared to controls (72% vs. 17%, p < 0.0001). GRBAS voice ratings were worse in the RDP cohort across nearly all categories. Dysarthria in RDP was associated with concordant cranial nerve 9-11 dysfunction (54%, p = 0.048), speech/swallowing dysfunction (96%, p = 0.0003); and oral dystonia (88%, p = 0.001). CONCLUSIONS: Quantitative voice and speech analyses are important in assessing RDP. Subjects frequently experience dysarthria and dysphonia. Dystonia is not the exclusive voice abnormality present in this population. In our analysis, RDP subjects more frequently experienced bulbar symptoms than controls. GRBAS scores are useful in quantifying voice impairment, potentially allowing for better assessments of progression or treatment effects. Future directions include using task-specific diagnostic and perceptual voice evaluation tools to further assess laryngeal dystonia.

The first Japanese case of primary familial brain calcification caused by an MYORG variant.

Primary familial brain calcification (PFBC) is a hereditary neurological disorder characterized by idiopathic calcification of the bilateral basal ganglia and other areas of the brain. MYORG has been identified as the first causative gene of autosomal recessive PFBC in Chinese families. There have been several reports of PFBC associated with MYORG (MYORG-PFBC) in individuals of Middle Eastern, European, and Latin American ancestry but to date, there have been no reported Japanese cases. We report the first Japanese case of MYORG-PFBC. The patient was a 43-year-old Japanese woman who experienced mild headaches and cerebellar ataxia including dysarthria. Computed tomography showed calcification in the cerebral white matter, basal ganglia, cerebellum, and brainstem. Using exome sequencing, we identified a homozygous variant in the MYORG gene (NM_020702.4: c.794C>T,p.Thr265Met). Our patient presented dysarthria and extensive calcification affecting the pons, which are specific features of MYORG-PFBC. We report clinical symptoms and imaging findings of a case with p.Thr265Met variant.

Choline transporter-like 1 deficiency causes a new type of childhood-onset neurodegeneration.

Cerebral choline metabolism is crucial for normal brain function, and its homoeostasis depends on carrier-mediated transport. Here, we report on four individuals from three families with neurodegenerative disease and homozygous frameshift mutations (Asp517Metfs*19, Ser126Metfs*8, and Lys90Metfs*18) in the SLC44A1 gene encoding choline transporter-like protein 1. Clinical features included progressive ataxia, tremor, cognitive decline, dysphagia, optic atrophy, dysarthria, as well as urinary and bowel incontinence. Brain MRI demonstrated cerebellar atrophy and leukoencephalopathy. Moreover, low signal intensity in globus pallidus with hyperintensive streaking and low signal intensity in substantia nigra were seen in two individuals. The Asp517Metfs*19 and Ser126Metfs*8 fibroblasts were structurally and functionally indistinguishable. The most prominent ultrastructural changes of the mutant fibroblasts were reduced presence of free ribosomes, the appearance of elongated endoplasmic reticulum and strikingly increased number of mitochondria and small vesicles. When chronically treated with choline, those characteristics disappeared and mutant ultrastructure resembled healthy control cells. Functional analysis revealed diminished choline transport yet the membrane phosphatidylcholine content remained unchanged. As part of the mechanism to preserve choline and phosphatidylcholine, choline transporter deficiency was implicated in impaired membrane homeostasis of other phospholipids. Choline treatments could restore the membrane lipids, repair cellular organelles and protect mutant cells from acute iron overload. In conclusion, we describe a novel childhood-onset neurometabolic disease caused by choline transporter deficiency with autosomal recessive inheritance.

A p.Arg499His Mutation in SPAST Is Associated with Infantile Onset Ascending Spastic Paralysis Complicated with Dysarthria and Anarthria.

The complication of anarthria in hereditary spastic paraplegia (HSP) patients has been reported to result from mutations in either ALS2 or FA2H. Here, we present a case of a 12-year-old boy with hereditary spastic paralysis and anarthria associated with a SPAST mutation. Initial presentation was at 14 months of age, when the patient experienced leg stiffness. At 3 years of age, he could speak well using sentences. At 9 years of age, he was found to have dysarthria and had difficulty writing. At 12 years of age, the ability to speak was lost. The patient could not vocalize any words, despite contraction of his neck and respiratory muscles during attempted vocalization. Additionally, the patient has never walked independently in his life. Considering these symptoms, we diagnosed him as having infantile onset ascending hereditary spastic paralysis (IAHSP) complicated with anarthria. By whole-exome sequencing, we discovered a heterozygous SPAST mutation c.1496G > A (p.Arg499His), which was not found in the parents and is probably de novo. This mutation was already repeatedly described with similar phenotype. Our results suggest that the p.Arg499His mutation in SPAST should be considered as a differential diagnosis in IAHSP.

Identification of extremely rare mitochondrial disorders by whole exome sequencing.

Whole exome sequencing (WES) is an effective tool for the genetic diagnosis of mitochondrial disorders due to various nuclear genetic defects. In this study, three patients affected by extremely rare mitochondrial disorders caused by nuclear genetic defects are described. The medical records of each patient were reviewed to obtain clinical symptoms, results of biochemical and imaging studies, and muscle biopsies. WES and massive parallel sequencing of whole mtDNA were performed for each patient. The oxygen consumption rate (OCR) and complex activity I and IV was measured. Patients 1 and 2 had exhibited global developmental delay and seizure since early infancy. Blood lactate, the lactate-to-pyruvate ratio, and urinary excretion of Krebs cycle intermediates were markedly elevated. Patient 1 also was noted for ophthalmoplegia. Patient 2 had left ventricular hypertrophy and ataxia. Patient 3 developed dysarthria, gait disturbance, and right-side weakness at age 29. Brain magnetic resonance imaging demonstrated abnormal signal intensity involving the bilateral thalami, midbrain, or pons. Based on WES, patient 1 had p.Glu415Gly and p.Arg484Trp variants in MTO1. In patient 2, p.Gln111ThrfsTer5 and RNA mis-splicing were identified in TSFM. Patient 3 carried p.Met151Thr and p.Met246Lys variants in AARS2. Skin fibroblasts of three patients exhibited decreased OCRs and complex 1 activity, and mitochondrial DNA was normal. These results demonstrate the utility of WES for identifying the genetic cause of extremely rare mitochondrial disorders, which has implications for genetic counseling.

TANGO2 deficiency as a cause of neurodevelopmental delay with indirect effects on mitochondrial energy metabolism.

Exome sequencing has recently identified mutations in the gene TANGO2 (transport and Golgi organization 2) as a cause of developmental delay associated with recurrent crises involving rhabdomyolysis, cardiac arrhythmias, and metabolic derangements. The disease is not well understood, in part as the cellular function and subcellular localization of the TANGO2 protein remain unknown. Furthermore, the clinical syndrome with its heterogeneity of symptoms, signs, and laboratory findings is still being defined. Here, we describe 11 new cases of TANGO2-related disease, confirming and further expanding the previously described clinical phenotype. Patients were homozygous or compound heterozygous for previously described exonic deletions or new frameshift, splice site, and missense mutations. All patients showed developmental delay with ataxia, dysarthria, intellectual disability, or signs of spastic diplegia. Of importance, we identify two subjects (aged 12 and 17 years) who have never experienced any overt episode of the catabolism-induced metabolic crises typical for the disease. Mitochondrial complex II activity was mildly reduced in patients investigated in association with crises but normal in other patients. In one deceased patient, post-mortem autopsy revealed heterotopic neurons in the cerebral white matter, indicating a possible role for TANGO2 in neuronal migration. Furthermore, we have addressed the subcellular localization of several alternative isoforms of TANGO2, none of which were mitochondrial but instead appeared to have a primarily cytoplasmic localization. Previously described aberrations in Golgi morphology were not observed in cultured skin fibroblasts.

Ataxia and dysarthria due to an ABCA2 variant: Extension of the phenotypic spectrum.

INTRODUCTION: Ataxias are heterogeneous disorders that are caused by variants in a large number of genes. The study was conducted to identify the molecular basis of a movement disorder in a consanguineous Pakistani family. METHODS: We performed clinical assessments and magnetic resonance imaging of the older of two siblings affected with a movement disorder. Molecular analyses included whole-exome sequencing in order to delineate the underlying pathology of the disorder. Segregation of variants with the phenotype was checked by Sanger sequencing. RESULTS: Symptoms of the two affected subjects were consistent with cerebellar ataxia with dysarthria. Magnetic resonance imaging did not reveal brain abnormalities. The levels of low density lipid proteins were elevated in blood samples of both affected individuals. Whole-exome sequencing data analyses identified a frameshift variant, c.4993delG:p.(Val1665TyrfsTer36) in ABCA2 (NM_212533.2) which segregated with the disorder and was absent from all publicly available databases and ethnically matched controls. Although recessively inherited ABCA2 variants have been reported in two patients who had intellectual disability with global developmental delays, our study demonstrates the role of an ABCA2 variant in the pathogenesis of ataxia with dysarthria. The phenotype observed in our patients shows high concordance with that observed in Abca2 knockout mice. CONCLUSION: Our research links an ABCA2 variant with a distinct form of ataxia with dysarthria in humans and demonstrates pleiotropic effects due to the gene mutation. The findings further delineate the importance of low density lipid metabolism and intracellular sterol trafficking in brain function.

Primary familial brain calcification caused by a novel homozygous MYORG mutation in a consanguineous Italian family.

Primary familial brain calcification (PFBC) is a rare disorder mostly characterized by calcium deposits in the basal ganglia and a wide spectrum of neurologic and psychiatric symptoms, typically inherited as an autosomal dominant trait. Recently, MYORG was reported as the first autosomal recessive causal gene in PFBC patients of Chinese and Middle Eastern origin. Herein, we describe the first PFBC patient of European descent found to carry a novel homozygous MYORG mutation (p.N511Tfs*243). Interestingly, the patient's father, a heterozygous carrier of the same mutation, showed diffuse bilateral cerebral calcifications with no symptoms other than very mild postural tremor.

Novel pathogenic COX20 variants causing dysarthria, ataxia, and sensory neuropathy.

COX20/FAM36A encodes a mitochondrial complex IV assembly factor important for COX2 activation. Only one homozygous COX20 missense mutation has been previously described in two separate consanguineous families. We report four subjects with features that include childhood hypotonia, areflexia, ataxia, dysarthria, dystonia, and sensory neuropathy. Exome sequencing in all four subjects identified the same novel COX20 variants. One variant affected the splice donor site of intron-one (c.41A>G), while the other variant (c.157+3G>C) affected the splice donor site of intron-two. cDNA and protein analysis indicated that no full-length cDNA or protein was generated. These subjects expand the phenotype associated with COX20 deficiency.

Genetic and phenotypic profile of 112 patients with X-linked Charcot-Marie-Tooth disease type 1.

BACKGROUND AND PURPOSE: X-linked Charcot-Marie-Tooth disease type 1 (CMTX1), caused by mutations in gap junction protein beta 1 (GJB1), is characterized by various central nervous system symptoms and gender differences of clinical severity. The aim of this study was to identify the frequency and mutation spectrum of CMTX1 patients in Japan and to demonstrate their phenotypic diversities. METHODS: Using three high-throughput sequencing systems, targeted gene panel sequencing on 1483 unrelated index patients with suspected Charcot-Marie-Tooth (CMT) disease was performed. The peripheral and central nervous system involvements of all patients with GJB1 variants were assessed retrospectively and a detailed gender comparison was conducted with the CMT examination score. RESULTS: Twenty-three novel and 36 described GJB1 variants were identified from 88 pedigrees, in which 34 female and 78 male patients were enrolled. Mean age at onset of the male patients was much younger than the females, 21.56 ± 17.63 years vs. 35.53 ± 23.72 years (P = 0.007). Male patients presented with more severe phenotypes in every examination item, but statistical differences were observed only in motor dysfunctions of the lower extremities and vibration sensation. No significant sensory difference was identified between genders, either clinically or electrophysiologically. Central nervous system dysfunctions were found in 15 patients from 12 pedigrees. Therein, six patients developed stroke-like phenotypes, with dysarthria as the leading symptom. CONCLUSIONS: A relatively lower frequency of CMTX1 (5.9%) was demonstrated and a broad mutation spectrum of GJB1 was described. Detailed clinical differences between genders and various central nervous system symptoms were also illustrated, even in the same pedigree.

[GNAO1: a new gene to consider on early-onset childhood dystonia]. / GNAO1: un nuevo gen a considerar en la distonia temprana de la infancia.

TITLE: GNAO1: un nuevo gen a considerar en la distonia temprana de la infancia.

Upstream Stimulating Factor 1 (USF-1) Gene Polymorphisms and the Risk, Symptoms, and Outcome of Pediatric Ischemic Stroke.

BACKGROUND: Pediatric ischemic stroke is an important cause of morbidity and mortality. As previous studies of children after stroke showed, dyslipidemias were very common in Polish and other European populations. Thus, looking for genetic factors predisposing to pediatric stroke, its symptoms, and outcome, we have analyzed 2 polymorphisms of the upstream stimulating factor 1 (USF-1) gene. MATERIALS AND METHODS: The study group consisted of 82 children with stroke, 156 parents, and 146 controls. We used 2 alternative methods: the case-control model and the analysis of families using the transmission disequilibrium test. The 2 polymorphisms, rs2516839 and rs3737787, were genotyped using the TaqMan Pre-Designed SNP Genotyping Assay. The Statistica 10.0 software was used in all statistical analyses. RESULTS: We did not observe any statistical differences in genotype and allele frequencies between patients and controls. There were also no significant differences in the transmission of alleles from the parents to the affected children. However, we have observed that the TT genotype of the rs2516839 polymorphism was more common in patients with epilepsy and dysarthria, whereas the TT genotype of the rs3737787 polymorphism was more frequent in the group of patients with a decrease in intellectual functioning. CONCLUSIONS: Our study did not show any associations between the 2 analyzed polymorphisms of the USF-1 gene and pediatric ischemic stroke. However, we have observed an influence of specific genotypes on the outcome of stroke, including epilepsy, dysarthria, and a decrease in intellectual functioning.

A recurrent de novo missense mutation in UBTF causes developmental neuroregression.

UBTF (upstream binding transcription factor) exists as two isoforms; UBTF1 regulates rRNA transcription by RNA polymerase 1, whereas UBTF2 regulates mRNA transcription by RNA polymerase 2. Herein, we describe 4 patients with very similar patterns of neuroregression due to recurrent de novo mutations in UBTF (GRCh37/hg19, NC_000017.10: g.42290219C > T, NM_014233.3: c.628G > A) resulting in the same amino acid change in both UBTF1 and UBTF2 (p.Glu210Lys [p.E210K]). Disease onset in our cohort was at 2.5 to 3 years and characterized by slow progression of global motor, cognitive and behavioral dysfunction. Notable early features included hypotonia with a floppy gait, high-pitched dysarthria and hyperactivity. Later features included aphasia, dystonia, and spasticity. Speech and ambulatory ability were lost by the early teens. Magnetic resonance imaging showed progressive generalized cerebral atrophy (supratentorial > infratentorial) with involvement of both gray and white matter. Patient fibroblasts showed normal levels of UBTF transcripts, increased expression of pre-rRNA and 18S rRNA, nucleolar abnormalities, markedly increased numbers of DNA breaks, defective cell-cycle progression, and apoptosis. Expression of mutant human UBTF1 in Drosophila neurons was lethal. Although no loss-of-function variants are reported in the Exome Aggregation Consortium (ExAC) database and Ubtf-/- is early embryonic lethal in mice, Ubtf+/- mice displayed only mild motor and behavioral dysfunction in adulthood. Our data underscore the importance of including UBTF E210K in the differential diagnosis of neuroregression and suggest that mainly gain-of-function mechanisms contribute to the pathogenesis of the UBTF E210K neuroregression syndrome.

Novel SLC25A32 mutation in a patient with a severe neuromuscular phenotype.

In a 51-year-old patient of consanguineous parents with a severe neuromuscular phenotype of early-onset ataxia, myoclonia, dysarthria, muscle weakness and exercise intolerance, exome sequencing revealed a novel homozygous variant (c.-264_31delinsCTCACAAATGCTCA) in the mitochondrial FAD-transporter gene SLC25A32. Flavin adenine dinucleotide (FAD) is an essential co-factor for many mitochondrial enzymes and impaired mitochondrial FAD-transport was supported by a reduced oxidative phosphorylation complex II activity in the patient's muscle, decreased ATP production in fibroblasts, and a deficiency of mitochondrial FAD-dependent enzymes. Clinically, the patient showed improvement upon riboflavin treatment, which is a precursor of FAD. Our results confirm the recently reported case of SLC25A32 as a cause of riboflavin-responsive disease. Our patient showed a more severe clinical phenotype compared with the reported patient, corresponding with the (most likely) complete absence of the SLC25A32-encoding MFT (Mitochondrial Folate Transporter) protein.

Dysarthria and broader motor speech deficits in Dravet syndrome.

OBJECTIVE: To analyze the oral motor, speech, and language phenotype in 20 children and adults with Dravet syndrome (DS) associated with mutations in SCN1A. METHODS: Fifteen verbal and 5 minimally verbal DS patients with SCN1A mutations (aged 15 months-28 years) underwent a tailored assessment battery. RESULTS: Speech was characterized by imprecise articulation, abnormal nasal resonance, voice, and pitch, and prosody errors. Half of verbal patients had moderate to severely impaired conversational speech intelligibility. Oral motor impairment, motor planning/programming difficulties, and poor postural control were typical. Nonverbal individuals had intentional communication. Cognitive skills varied markedly, with intellectual functioning ranging from the low average range to severe intellectual disability. Language impairment was congruent with cognition. CONCLUSIONS: We describe a distinctive speech, language, and oral motor phenotype in children and adults with DS associated with mutations in SCN1A. Recognizing this phenotype will guide therapeutic intervention in patients with DS.