Clinical and Pathological Features of FTDP-17 with MAPT p.K298_H299insQ Mutation.

BACKGROUND: MAPT is a causative gene in frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17), a hereditary degenerative disease with various clinical manifestations, including progressive supranuclear palsy, corticobasal syndrome, Parkinson's disease, and frontotemporal dementia. OBJECTIVES: To analyze genetically, biochemically, and pathologically multiple members of two families who exhibited various phenotypes of the disease. METHODS: Genetic analysis included linkage analysis, homozygosity haplotyping, and exome sequencing. We conducted tau protein microtubule polymerization assay, heparin-induced tau aggregation, and western blotting with brain lysate from an autopsy case. We also evaluated abnormal tau aggregation by using anti-tau antibody and PM-PBB3. RESULTS: We identified a variant, c.896_897insACA, p.K298_H299insQ, in the MAPT gene of affected patients. Similar to previous reports, most patients presented with atypical parkinsonism. Biochemical analysis revealed that the mutant tau protein had a reduced ability to polymerize microtubules and formed abnormal fibrous aggregates. Pathological study revealed frontotemporal lobe atrophy, midbrain atrophy, depigmentation of the substantia nigra, and four-repeat tau-positive inclusions in the hippocampus, brainstem, and spinal cord neurons. The inclusion bodies also stained positively with PM-PBB3. CONCLUSIONS: This study confirmed that the insACA mutation caused FTDP-17. The affected patients showed symptoms resembling Parkinson's disease initially and symptoms of progressive supranuclear palsy later. Despite the initial clinical diagnosis of frontotemporal dementia in the autopsy case, the spread of lesions could explain the process of progressive supranuclear palsy. The study of more cases in the future will help clarify the common pathogenesis of MAPT mutations or specific pathogeneses of each mutation.

CGG repeat expansion in LRP12 in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by the degeneration of motor neurons. Although repeat expansion in C9orf72 is its most common cause, the pathogenesis of ALS isn't fully clear. In this study, we show that repeat expansion in LRP12, a causative variant of oculopharyngodistal myopathy type 1 (OPDM1), is a cause of ALS. We identify CGG repeat expansion in LRP12 in five families and two simplex individuals. These ALS individuals (LRP12-ALS) have 61-100 repeats, which contrasts with most OPDM individuals with repeat expansion in LRP12 (LRP12-OPDM), who have 100-200 repeats. Phosphorylated TDP-43 is present in the cytoplasm of iPS cell-derived motor neurons (iPSMNs) in LRP12-ALS, a finding that reproduces the pathological hallmark of ALS. RNA foci are more prominent in muscle and iPSMNs in LRP12-ALS than in LRP12-OPDM. Muscleblind-like 1 aggregates are observed only in OPDM muscle. In conclusion, CGG repeat expansions in LRP12 cause ALS and OPDM, depending on the length of the repeat. Our findings provide insight into the repeat length-dependent switching of phenotypes.

Spectra and characteristics of somatic mutations induced by ionizing radiation in hematopoietic stem cells.

Spectra and frequencies of spontaneous and X-ray-induced somatic mutations were revealed with mouse long-term hematopoietic stem cells (LT-HSCs) by whole-genome sequencing of clonal cell populations propagated in vitro from single isolated LT-HSCs. SNVs and small indels were the most common types of somatic mutations, and increased up to twofold to threefold by whole-body X-irradiation. Base substitution patterns in the SNVs suggested a role of reactive oxygen species in radiation mutagenesis, and signature analysis of single base substitutions (SBS) revealed a dose-dependent increase of SBS40. Most of spontaneous small deletions were shrinkage of tandem repeats, and X-irradiation specifically induced small deletions out of tandem repeats (non-repeat deletions). Presence of microhomology sequences in non-repeat deletions suggested involvement of microhomology mediated end-joining repair mechanisms as well as nonhomologous end-joining in radiation-induced DNA damages. We also identified multisite mutations and structural variants (SV), i.e., large indels, inversions, reciprocal translocations, and complex variants. The radiation-specificity of each mutation type was evaluated from the spontaneous mutation rate and the per-Gy mutation rate estimated by linear regression, and was highest with non-repeat deletions without microhomology, followed by those with microhomology, SV except retroelement insertions, and multisite mutations; these types were thus revealed as mutational signatures of ionizing radiation. Further analysis of somatic mutations in multiple LT-HSCs indicated that large fractions of postirradiation LT-HSCs originated from single LT-HSCs that survived the irradiation and then expanded in vivo to confer marked clonality to the entire hematopoietic system, with varying clonal expansion and dynamics depending on radiation dose and fractionation.

Massive expansion of multiple clones in the mouse hematopoietic system long after whole-body X-irradiation.

Clonal hematopoiesis (CH) is prevalent in the elderly and associates with hematologic malignancy and cardiovascular disease. Although the risk of developing these diseases increases with radiation doses in atomic-bomb survivors, the causal relationship between radiation exposure and CH is unclear. This study investigated whether radiation exposure induces CH in mice 12-18 months after 3-Gy whole-body irradiation. We found radiation-associated increases in peripheral blood myeloid cells and red blood cell distribution width (RDW). Deep sequencing of bone marrow and non-hematopoietic tissue cells revealed recurrent somatic mutations specifically in the hematopoietic system in 11 of 12 irradiated mice but none in 6 non-irradiated mice. The irradiated mice possessed mutations with variant allele frequencies (VAFs) of > 0.02 on an average of 5.8 per mouse; mutations with VAFs of > 0.1 and/or deletion were prevalent. Examining hematopoietic stem/progenitor cells in two irradiated mice revealed several mutations co-existing in the same clones and multiple independent clones that deliver 60-80% of bone marrow nuclear cells. Our results indicate development of massive CH due to radiation exposure. Moreover, we have characterized mutations in radiation-induced CH.

A Basic Study for Predicting Dysphagia in Panoramic X-ray Images Using Artificial Intelligence (AI)-Part 1: Determining Evaluation Factors and Cutoff Levels.

BACKGROUND: Dysphagia relates to quality of life; this disorder is related to the difficulties of dental treatment. PURPOSE: To detect radiographic signs of dysphagia by using panoramic radiograph with an AI system. METHODS: Seventy-seven patients who underwent a panoramic radiograph and a videofluorographic swallowing study were analyzed. Age, gender, the number of remaining teeth, the distance between the tongue and the palate, the vertical and horizontal hyoid bone position, and the width of the tongue were analyzed. Logistic regression analysis was used. For the statistically significant factors, the cutoff level was determined. The cutoff level was determined by using analysis of the receiver operations characteristic (ROC) curve and the Youden Index. RESULTS: A significant relationship with presence of dysphagia was only observed for the vertical hyoid bone position. The area under the curve (AUC) was 0.72. The cutoff level decided for the hyoid bone was observed to be lower than the mandibular border line. CONCLUSIONS: In cases where the hyoid bone is lower than the mandibular border line on a panoramic radiograph, it suggests the risk of dysphagia would be high. We will create an AI model for the detection of the risk of dysphagia by using the assessment of vertical hyoid bone position.

Kv11 (ether-à-go-go-related gene) voltage-dependent K+ channels promote resonance and oscillation of subthreshold membrane potentials.

KEY POINTS: Some ion channels are known to behave as inductors and make up the parallel resonant circuit in the plasma membrane of neurons, which enables neurons to respond to current inputs with a specific frequency (so-called 'resonant properties'). Here, we report that heterologous expression of mouse Kv11 voltage-dependent K+ channels generate resonance and oscillation at depolarized membrane potentials in HEK293 cells; expressions of individual Kv11 subtypes generate resonance and oscillation with different frequency properties. Kv11.3-expressing HEK293 cells exhibited transient conductance changes that opposed the current changes induced by voltage steps; this probably enables Kv11 channels to behave like an inductor. The resonance and oscillation of inferior olivary neurons were impaired at the resting membrane potential in Kv11.3 knockout mice. This study helps to elucidate basic ion channel properties that are crucial for the frequency responses of neurons. ABSTRACT: The plasma membranes of some neurons preferentially respond to current inputs with a specific frequency, and output as large voltage changes. This property is called resonance, and is thought to be mediated by ion channels that show inductor-like behaviour. However, details of the candidate ion channels remain unclear. In this study, we mainly focused on the functional roles of Kv11 potassium (K+ ) channels, encoded by ether-á-go-go-related genes, in resonance in mouse inferior olivary (IO) neurons. We transfected HEK293 cells with long or short splice variants of Kv11.1 (Merg1a and Merg1b) or Kv11.3, and examined membrane properties using whole-cell recording. Transfection with Kv11 channels reproduced resonance at membrane potentials depolarized from the resting state. Frequency ranges of Kv11.3-, Kv11.1(Merg1b)- and Kv11.1(Merg1a)-expressing cells were 2-6 Hz, 2-4 Hz, and 0.6-0.8 Hz, respectively. Responses of Kv11.3 currents to step voltage changes were essentially similar to those of inductor currents in the resistor-inductor-capacitor circuit. Furthermore, Kv11 transfections generated membrane potential oscillations. We also confirmed the contribution of HCN1 channels as a major mediator of resonance at more hyperpolarized potentials by transfection into HEK293 cells. The Kv11 current kinetics and properties of Kv11-dependent resonance suggested that Kv11.3 mediated resonance in IO neurons. This finding was confirmed by the impairment of resonance and oscillation at -30 to -60 mV in Kcnh7 (Kv11.3) knockout mice. These results suggest that Kv11 channels have important roles in inducing frequency-dependent responses in a subtype-dependent manner from resting to depolarized membrane potentials.

Zonisamide can ameliorate the voltage-dependence alteration of the T-type calcium channel CaV3.1 caused by a mutation responsible for spinocerebellar ataxia.

Spinocerebellar ataxia (SCA) 42 is caused by a mutation in CACNA1G, which encodes the low voltage-gated calcium channel CaV3.1 (T-type). Patients with SCA42 exhibit a pure form of cerebellar ataxia. We encountered a patient with the p.Arg1715His mutation, suffering from intractable resting tremor, particularly head tremor. This symptom improved with the administration of low-dose of zonisamide (ZNS), a T-type calcium channel blocker effective for treating Parkinson's disease and epilepsy. Previous electrophysiological studies showed that the voltage dependence of this mutant CaV3.1 was shifted toward the positive potential. This abnormal shift was considered a factor related to disease onset and symptoms. In this study, we performed whole-cell recordings of GFP-expressing HEK293T cells that expressed wild-type or mutant CaV3.1 and investigated the changes in the abnormal shift of voltage dependence of the mutant CaV3.1. The results showed that ZNS in an amount equivalent to the patient's internal dose significantly ameliorated the abnormal shift in the mutant CaV3.1, giving values close to those in the wild-type. On the other hand, ZNS did not affect the voltage dependence of wild-type CaV3.1. Because CaV3.1 is known to be involved in tremogenesis, modulation of the voltage dependence of mutant CaV3.1 by ZNS might have contributed to improvement in the intractable tremor of our patient with SCA42. Moreover, efonidipine, another T-type calcium channel blocker, had no effect on tremors in our patient with SCA42 and did not improve the abnormal shift in the voltage dependence of the mutant CaV3.1. This indicates that ZNS is distinct from other T-type calcium channel blockers in terms of modulation of the voltage dependence of the mutant CaV3.1.

Aggressive periodontitis and NOD2 variants.

Aggressive periodontitis (AgP) occurs at an early age and causes rapid periodontal tissue destruction. Nucleotide-binding oligomerization domain-containing protein 2 (NOD2) encodes a protein with two caspase recruitment domains and eleven leucine-rich repeats. This protein is expressed mainly in peripheral blood leukocytes and is involved in immune response. NOD2 variants have been associated with increased susceptibility to Crohn's disease, and recently, NOD2 was reported as a causative gene in AgP. The present study aimed to identify potential NOD2 variants in an AgP cohort (a total of 101 patiens: 37 patients with positive family histories and 64 sporadic patients). In the familial group, six patients from two families had a reported heterozygous missense variant (c.C931T, p.R311W). Four patients in the sporadic group had a heterozygous missense variant (c.C1411T, p.R471C), with no reported association to the disease. Overall, two NOD2 variants, were identified in 10% of our AgP cohort. These variants were different from the major variants reported in Crohn's disease. More cases need to be investigated to elucidate the role of NOD2 variants in AgP pathology.

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.

Middle-age-onset cerebellar ataxia caused by a homozygous TWNK variant: a case report.

BACKGROUND: The TWNK gene encodes the twinkle protein, which is a mitochondrial helicase for DNA replication. The dominant TWNK variants cause progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant 3, while the recessive variants cause mitochondrial DNA depletion syndrome 7 and Perrault syndrome 5. Perrault syndrome is characterized by sensorineural hearing loss in both males and females and gonadal dysfunction in females. Patients with Perrault syndrome may present early-onset cerebellar ataxia, whereas middle-age-onset cerebellar ataxia caused by TWNK variants is rare. CASE PRESENTATION: A Japanese female born to consanguineous parents presented hearing loss at age 48, a staggering gait at age 53, and numbness in her distal extremities at age 57. Neurological examination revealed sensorineural hearing loss, cerebellar ataxia, decreased deep tendon reflexes, and sensory disturbance in the distal extremities. Laboratory tests showed no abnormal findings other than a moderate elevation of pyruvate concentration levels. Brain magnetic resonance imaging revealed mild cerebellar atrophy. Using exome sequencing, we identified a homozygous TWNK variant (NM_021830: c.1358G>A, p.R453Q). CONCLUSIONS: TWNK variants could cause middle-age-onset cerebellar ataxia. Screening for TWNK variants should be considered in cases of cerebellar ataxia associated with deafness and/or peripheral neuropathy, even if the onset is not early.

Optineurin regulates osteoblastogenesis through STAT1.

A sophisticated and delicate balance between bone resorption by osteoclasts and bone formation by osteoblasts regulates bone metabolism. Optineurin (OPTN) is a gene involved in primary open-angle glaucoma and amyotrophic lateral sclerosis. Although its function has been widely studied in ophthalmology and neurology, recent reports have shown its possible involvement in bone metabolism through negative regulation of osteoclast differentiation. However, little is known about the role of OPTN in osteoblast function. Here, we demonstrated that OPTN controls not only osteoclast but also osteoblast differentiation. Different parameters involved in osteoblastogenesis and osteoclastogenesis were assessed in Optn-/- mice. The results showed that osteoblasts from Optn-/- mice had impaired alkaline phosphatase activity, defective mineralized nodules, and inability to support osteoclast differentiation. Moreover, OPTN could bind to signal transducer and activator of transcription 1 (STAT1) and regulate runt-related transcription factor 2 (RUNX2) nuclear localization by modulating STAT1 levels in osteoblasts. These data suggest that OPTN is involved in bone metabolism not only by regulating osteoclast function but also by regulating osteoblast function by mediating RUNX2 nuclear translocation via STAT1.

Biallelic mutation of HSD17B4 induces middle age-onset spinocerebellar ataxia.

OBJECTIVE: To determine the genetic underpinnings of slowly progressive spinocerebellar ataxia, autosomal recessive (SCAR), we performed exome analysis and examined the relationship between clinical severity and functional change induced by the mutation. METHODS: Homozygosity fingerprinting and exome sequencing were performed to identify causative mutations in 2 consanguineous families. We assessed the expression of D-bifunctional protein (DBP) and the amount of dimerized DBP in fibroblasts by immunoblot and quantitative reverse transcription PCR. The pathogenicity of the mutation was evaluated using the Combined Annotation-Dependent Depletion (CADD) scores; these results were compared with the scores of previously reported mutations. RESULTS: We identified a homozygous mutation as causative of middle age-onset SCAR: p.Ala175Thr, which is located in HSD17B4 that encodes peroxisomal DBP. The patients developed cerebellar ataxia, and the subsequent progression was slow. The symptoms presented were milder than those in previously reported cases. The messenger RNA expression levels were normal, but protein levels were diminished. Dimerization of DBP was also reduced. The CADD score of the identified mutation was lower than those of previously reported mutations. CONCLUSIONS: This is the report of middle age-onset DBP deficiency. Residual functional DBP caused relatively mild symptoms in the affected patients, i.e., slowly progressive ataxia and hearing loss. This study broadens the scope of DBP deficiency phenotypes and indicates that CADD scores may be used to estimate the severity of DBP deficiencies.

Genetic screening for potassium channel mutations in Japanese autosomal dominant spinocerebellar ataxia.

Spinocerebellar ataxia (SCA) is a genetically heterogeneous disease characterized by cerebellar ataxia. Many causative genes have been identified to date, the most common etiology being the abnormal expansion of repeat sequences, and the mutation of ion channel genes also play an important role in the development of SCA. Some of them encode calcium and potassium channels. However, due to limited reports about potassium genes in SCA, we screened 192 Japanese individuals with dominantly inherited SCA who had no abnormal repeat expansions of causative genes for potassium channel mutations (KCNC3 for SCA13 and KCND3 for SCA19/SCA22) by target sequencing. As a result, two variants were identified from two patients: c.1973G>A, p.R658Q and c.1018G>A, p.V340M for KCNC3, and no pathogenic variant was identified for KCND3. The newly identified p.V340M exists in the extracellular domain, and p.R658Q exists in the intracellular domain on the C-terminal side, although most of the reported KCNC3 mutations are present at the transmembrane site. Adult-onset and slowly progressive cerebellar ataxia are the main clinical features of SCA13 and SCA19 caused by potassium channel mutations, which was similar in our cases. SCA13 caused by KCNC3 mutations may present with deep sensory loss and cognitive impairment in addition to cerebellar ataxia. In this study, mild deep sensory loss was observed in one case. SCA caused by potassium channel gene mutations is extremely rare, and more cases should be accumulated in the future to elucidate its pathogenesis due to channel dysfunction.

Ligand-Controlled Stereodivergent, Enantioselective Conjugate Addition of 2-Oxazoline- and 2-Thiazoline-4-carboxylate to Nitroalkene Catalyzed by Chiral Copper Complexes.

The copper-catalyzed asymmetric conjugate addition of 2-oxazoline- and 2-thiazoline-4-carboxylate to a nitroalkene proceeded to give either the syn or anti adduct selectively in high enantiomeric excess when an appropriate chiral ligand was used. Subsequent reduction of the nitro group followed by hydrolysis of the oxazoline ring yielded an optically active γ-lactam of protected α-quaternary serine derivative.

Radiopacity Measurement of Restorative Resins Using Film and Three Digital Systems for Comparison with ISO 4049: International Standard.

This study compared Ultra Speed Occlusal Film (USOF) and 3 digital systems in determining the radiopacity of 5 different restorative resins in terms of equivalents of aluminum thickness. Whether those digital systems could be used to determine whether radiopacity was in line with International Organization for Standardization (ISO) recommendations was also investigated. Disks of each of 5 restorative resins and an aluminum step wedge were exposed at 65 kVp and 10 mA on USOF and imaged with each digital system. Optical density on the film was measured with a transmission densitometer and the gray values on the digital images using Image J software. Graphs showing gray value/optical density to step wedge thickness were constructed. The aluminum equivalent was then calculated for all the resins using a regression equation. All the resins were more radiopaque than 1 mm of aluminum, and therefore met the ISO 4049 recommendations for restorative resins. Some resins showed statistically higher aluminum equivalents with digital imaging. The use of traditional X-ray films is declining, and digital systems offer many advantages, including an easy, fast, and reliable means of determining the radiopacity of dental materials.

A mutation in the low voltage-gated calcium channel CACNA1G alters the physiological properties of the channel, causing spinocerebellar ataxia.

BACKGROUND: Spinocerebellar ataxia (SCA) is a genetically heterogeneous disease. To date, 36 dominantly inherited loci have been reported, and 31 causative genes have been identified. RESULTS: In this study, we analyzed a Japanese family with autosomal dominant SCA using linkage analysis and exome sequencing, and identified CACNA1G, which encodes the calcium channel CaV3.1, as a new causative gene. The same mutation was also found in another family with SCA. Although most patients exhibited the pure form of cerebellar ataxia, two patients showed prominent resting tremor in addition to ataxia. CaV3.1 is classified as a low-threshold voltage-dependent calcium channel (T-type) and is expressed abundantly in the central nervous system, including the cerebellum. The mutation p.Arg1715His, identified in this study, was found to be located at S4 of repeat IV, the voltage sensor of the CaV3.1. Electrophysiological analyses revealed that the membrane potential dependency of the mutant CaV3.1 transfected into HEK293T cells shifted toward a positive potential. We established induced pluripotent stem cells (iPSCs) from fibroblasts of the patient, and to our knowledge, this is the first report of successful differentiation from the patient-derived iPSCs into Purkinje cells. There was no significant difference in the differentiation status between control- and patient-derived iPSCs. CONCLUSIONS: To date, several channel genes have been reported as causative genes for SCA. Our findings provide important insights into the pathogenesis of SCA as a channelopathy.

Characteristic findings on panoramic radiography and cone-beam CT to predict paresthesia after extraction of impacted third molar.

The purpose of this study was to compare findings on the relationship between impacted molar roots and the mandibular canal in panoramic and three-dimensional cone-beam CT (CBCT) images to identify those that indicated risk of postoperative paresthesia. The relationship between impacted molars and the mandibular canal was first classified using panoramic images. Only patients in whom the molar roots were either in contact with or superimposed on the canal were evaluated using CBCT. Of 466 patients examined using both panoramic and CBCT images, 280 underwent surgical extraction of an impacted molar, and 15 of these (5%) reported postoperative paresthesia. The spatial relationship between the impacted third molar root and the mandibular canal was determined by examining para-sagittal sections (lingual, buccal, inter-radicular, inferior, and combinations) obtained from the canal to the molar root and establishing the proximity of the canal to the molar root (in contact with or without loss of the cortical border and separate). The results revealed that darkening of the roots with interruption of the mandibular canal on panoramic radiographs and the inter-radicular position of the canal in CBCT images were characteristic findings indicative of risk of postoperative paresthesia. These results suggest that careful surgical intervention is required in patients with the above characteristics.