GGC Repeat Expansion of NOTCH2NLC in Adult Patients with Leukoencephalopathy.

Leukoencephalopathies comprise a broad spectrum of disorders, but the genetic background of adult leukoencephalopathies has rarely been assessed. In this study, we analyzed 101 Japanese patients with genetically unresolved adult leukoencephalopathy using whole-exome sequencing and repeat-primed polymerase chain reaction for detecting GGC expansion in NOTCH2NLC. NOTCH2NLC was recently identified as the cause of neuronal intranuclear inclusion disease. We found 12 patients with GGC expansion in NOTCH2NLC as the most frequent cause of adult leukoencephalopathy followed by NOTCH3 variants in our cohort. Furthermore, we found 1 case with de novo GGC expansion, which might explain the underlying pathogenesis of sporadic cases. ANN NEUROL 2019;86:962-968.

Biallelic TBCD Mutations Cause Early-Onset Neurodegenerative Encephalopathy.

We describe four families with affected siblings showing unique clinical features: early-onset (before 1 year of age) progressive diffuse brain atrophy with regression, postnatal microcephaly, postnatal growth retardation, muscle weakness/atrophy, and respiratory failure. By whole-exome sequencing, we identified biallelic TBCD mutations in eight affected individuals from the four families. TBCD encodes TBCD (tubulin folding co-factor D), which is one of five tubulin-specific chaperones playing a pivotal role in microtubule assembly in all cells. A total of seven mutations were found: five missense mutations, one nonsense, and one splice site mutation resulting in a frameshift. In vitro cell experiments revealed the impaired binding between most mutant TBCD proteins and ARL2, TBCE, and ß-tubulin. The in vivo experiments using olfactory projection neurons in Drosophila melanogaster indicated that the TBCD mutations caused loss of function. The wide range of clinical severity seen in this neurodegenerative encephalopathy may result from the residual function of mutant TBCD proteins. Furthermore, the autopsied brain from one deceased individual showed characteristic neurodegenerative findings: cactus and somatic sprout formations in the residual Purkinje cells in the cerebellum, which are also seen in some diseases associated with mitochondrial impairment. Defects of microtubule formation caused by TBCD mutations may underlie the pathomechanism of this neurodegenerative encephalopathy.

Matrin 3 Is a Component of Neuronal Cytoplasmic Inclusions of Motor Neurons in Sporadic Amyotrophic Lateral Sclerosis.

Mutations in the MATR3 gene have been identified as a cause of familial amyotrophic lateral sclerosis, but involvement of the matrin 3 (MATR3) protein in sporadic amyotrophic lateral sclerosis (SALS) pathology has not been fully assessed. We immunohistochemically analyzed MATR3 pathology in the spinal cords of SALS and control autopsy specimens. MATR3 immunostaining of the motor neuron nuclei revealed two distinct patterns: mild and strong staining. There were no differences in the ratio of mild versus strong nuclear staining between the SALS and control cases. MATR3-containing neuronal cytoplasmic inclusions (NCIs) were observed in 60% of SALS cases. Most motor neurons with MATR3-positive NCIs exhibited a mild nuclear staining pattern. Although 16.8% of NCIs positive for transactivating response region DNA-binding protein 43 (TDP-43) were estimated as double-labeled by MATR3, no MATR3-positive or TDP-43-negative NCIs were observed. Although a previous study found that MATR3-positive NCIs are present only in cases with C9orf72 hexanucleotide repeat expansion, ubiquitin-positive granular NCIs were not observed in the cerebellum, which have been reported as specific to C9orf72-related ALS. Six ALS cases were confirmed to be negative for the GGGGCC hexanucleotide. Our results reveal that MATR3 is a component of TDP-43-positive NCIs in motor neurons, even in SALS, and indicate the broader involvement of MATR3 in ALS pathology and the heterogeneity of TDP-43-positive NCIs.

Cerebrospinal fluid level of Nogo receptor 1 antagonist lateral olfactory tract usher substance (LOTUS) correlates inversely with the extent of neuroinflammation.

BACKGROUND: Although inflammation in the central nervous system is responsible for multiple neurological diseases, the lack of appropriate biomarkers makes it difficult to evaluate inflammatory activities in these diseases. Therefore, a new biomarker reflecting neuroinflammation is required for accurate diagnosis, appropriate therapy, and comprehension of pathogenesis of these neurological disorders. We previously reported that the cerebrospinal fluid (CSF) concentration of lateral olfactory tract usher substance (LOTUS), which promotes axonal growth as a Nogo receptor 1 antagonist, negatively correlates with disease activity in multiple sclerosis, suggesting that variation in LOTUS reflects the inflammatory activities and is a useful biomarker to evaluate the disease activity. To extend this observation, we analyzed the variation of LOTUS in the CSF of patients with bacterial and viral meningitis, which are the most common neuroinflammatory diseases. METHODS: CSF samples were retrospectively obtained from patients with meningitis (n = 40), who were followed up by CSF study at least twice, and from healthy controls (n = 27). Patients were divided into bacterial (n = 14) and viral meningitis (n = 18) after exclusion of eight patients according to the criteria of this study. LOTUS concentrations, total protein levels, and CSF cell counts in the acute and recovery phases were analyzed chronologically. We also used lipopolysaccharide-injected mice as a model of neuroinflammation to evaluate LOTUS mRNA and protein expression in the brain. RESULTS: Regardless of whether meningitis was viral or bacterial, LOTUS concentrations in the CSF of patients in acute phase were lower than those of healthy controls. As the patients recovered from meningitis, LOTUS levels in the CSF returned to the normal range. Lipopolysaccharide-injected mice also exhibited reduced LOTUS mRNA and protein expression in the brain. CONCLUSIONS: CSF levels of LOTUS correlated inversely with disease activity in both bacterial and viral meningitis, as well as in multiple sclerosis, because neuroinflammation downregulated LOTUS expression. Our data strongly suggest that variation of CSF LOTUS is associated with neuroinflammation and is useful as a biomarker for a broader range of neuroinflammatory diseases.

Cerebellar ataxia-dominant phenotype in patients with ERCC4 mutations.

Autosomal recessive cerebellar ataxias (ARCAs) are clinically and genetically heterogeneous neurological disorders. Through whole-exome sequencing of Japanese ARCA patients, we identified three index patients from unrelated families who had biallelic mutations in ERCC4. ERCC4 mutations have been known to cause xeroderma pigmentosum complementation group F (XP-F), Cockayne syndrome, and Fanconi anemia phenotypes. All of the patients described here showed very slowly progressive cerebellar ataxia and cognitive decline with choreiform involuntary movement, with young adolescent or midlife onset. Brain MRI demonstrated atrophy that included the cerebellum and brainstem. Of note, cutaneous symptoms were very mild: there was normal to very mild pigmentation of exposed skin areas and/or an equivocal history of pathological sunburn. However, an unscheduled DNA synthesis assay of fibroblasts from the patient revealed impairment of nucleotide excision repair. A similar phenotype was very recently recognized through genetic analysis of Caucasian cerebellar ataxia patients. Our results confirm that biallelic ERCC4 mutations cause a cerebellar ataxia-dominant phenotype with mild cutaneous symptoms, possibly accounting for a high proportion of the genetic causes of ARCA in Japan, where XP-F is prevalent.

De Novo Truncating Mutation of TRIM8 Causes Early-Onset Epileptic Encephalopathy.

BACKGROUND: Early-onset epileptic encephalopathy (EOEE) is a heterogeneous group of neurodevelopmental disorders characterised by infantile-onset intractable epilepsy and unfavourable developmental outcomes. Hundreds of mutations have been reported to cause EOEE; however, little is known about the clinical features of individuals with rare variants. CASE REPORT AND METHODS: We present a 10-year-old boy with severe developmental delay. He started experiencing recurrent focal seizures at 2 months old. Serial electroencephalograms persistently detected epileptiform discharges from the left hemisphere. Whole-exome sequencing and array-comparative genome hybridization were performed to search for de novo variations. Two-week-old C57Bl/6 mice were used for immunofluorescence studies. RESULTS: This case had a paternally inherited, 0.2-Mb duplication at chromosome 22q11.22. The whole-exome sequencing identified a de novo truncating mutation of tripartite motif containing 8 (TRIM8) (NM_030912:c.1099_1100insG:p.C367fs), one of the epileptic encephalopathy-associated genes. We verified that the murine homologues of these genes are expressed in the postnatal mouse brain. CONCLUSION: This is the second case of EOEE caused by a de novo truncating mutation of TRIM8. Further studies are required to determine the functional roles of TRIM8 in the postnatal development of the human brain and its functional relationships with other EOEE-associated genes.

De novo KCNH1 mutations in four patients with syndromic developmental delay, hypotonia and seizures.

The voltage-gated Kv10.1 potassium channel, also known as ether-a-go-go-related gene 1, encoded by KCNH1 (potassium voltage-gated channel, subfamily H (eag related), member 1) is predominantly expressed in the central nervous system. Recently, de novo missense KCNH1 mutations have been identified in six patients with Zimmermann-Laband syndrome and in four patients with Temple-Baraitser syndrome. These syndromes were historically considered distinct. Here we report three de novo missense KCNH1 mutations in four patients with syndromic developmental delay and epilepsy. Two novel KCNH1 mutations (p.R357Q and p.R357P), found in three patients, were located at the evolutionally highly conserved arginine in the channel voltage-sensor domain (S4). Another mutation (p.G496E) was found in the channel pore domain (S6) helix, which acts as a hinge in activation gating and mainly conducts non-inactivating outward potassium current. A previously reported p.G496R mutation was shown to produce no voltage-dependent outward current in CHO cells, suggesting that p.G496E may also disrupt the proper function of the Kv channel pore. Our report confirms that KCNH1 mutations are associated with syndromic neurodevelopmental disorder, and also support the functional importance of the S4 domain.

De novo missense mutations in NALCN cause developmental and intellectual impairment with hypotonia.

Three recessive mutations in the sodium leak channel, nonselective (NALCN) have been reported to cause intellectual disability and hypotonia. In addition, 14 de novo heterozygous mutations have been identified in 15 patients with arthrogryposis and neurodevelopmental impairment. Here, we report three patients with neurodevelopmental disease and hypotonia, harboring one recurrent (p.R1181Q) and two novel mutations (p.L312V and p.V1020F) occurring de novo in NALCN. Mutation p.L312 is located in the pore forming S6 region of domain I and p.V1020F in the S5 region of domain III. Mutation p.R1181Q is in a linker region. Mapping these three mutations to a model of NALCN showed p.Leu312 and p.Val1020 positioned in the hydrophobic core of the pore modules, indicating these two mutations may affect the gating function of NALCN. Although p.R1181Q is unlikely to affect the ion channel structure, previous studies have shown that an analogous mutation in Caenorhabditis elegans produced a phenotype with a coiling locomotion, suggesting that p.R1181Q could also affect NALCN function. Our three patients showed profound intellectual disability and growth delay, facial dysmorphologies and hypotonia. The present data support previous work suggesting heterozygous NALCN mutations lead to syndromic neurodevelopmental impairment.

De novo p.Arg756Cys mutation of ATP1A3 causes an atypical form of alternating hemiplegia of childhood with prolonged paralysis and choreoathetosis.

BACKGROUND: Alternating hemiplegia of childhood (AHC) is a rare neurological disorder that manifests recurrent attacks of hemiplegia, oculogyric, and choreoathetotic involuntary movements. De novo mutations in ATP1A3 cause three types of neurological diseases: AHC; rapid-onset dystonia-Parkinsonism (RDP); and cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss (CAPOS) syndromes. It remains to be determined whether or not a rare mutation in ATP1A3 may cause atypical phenotypes. CASE PRESENTATION: A 7-year-old boy presented with recurrent symptoms of generalized paralysis since 1 year and 5 months of age. Hypotonia, dystonia, and choreoathetosis persisted with exacerbation under febrile conditions, but no cerebellar ataxia had ever evolved in 6 years. Whole-exome sequencing (WES) was performed to determine his genetic background, and mutations were validated by the Sanger method. Crude protein extracts were prepared from the cultured cells, and expression of the wild-type or mutant ATP1A3 proteins were analyzed by Western blotting. WES identified a de novo pathogenic mutation in ATP1A3 (c.2266C > T:p.R756C) for this patient. A literature overview of two reported cases with p.R756C and p.R756H mutations showed both overlapping and distinct phenotypes when compared with those of the present case. The expression of the mutant form (R756C) of ATP1A3 did not differ markedly from that of the wild-type and D801N proteins. CONCLUSIONS: This study confirmed that p.R756C mutation of ATP1A3 cause atypical forms of AHC-associated disorders. The wide spectra of neurological phenotypes in AHC are linked to as-yet-unknown deficits in the functions of mutant ATP1A3.

A case of autism spectrum disorder arising from a de novo missense mutation in POGZ.

Autism spectrum disorder (ASD) is a clinically heterogeneous psychiatric disorder with various genetic backgrounds. Here, we report a novel mutation in the pogo transposable element-derived protein with zinc finger domain gene (POGZ) identified by trio-based whole exome sequencing. To date, a total of seven de novo POGZ mutations in ASD have been reported. POGZ contains a total of five functional domains, and this study reports the first de novo missense mutation in the centromere protein B-like DNA-binding domain. POGZ is highly expressed in the human fetal brain and is involved in mitosis and the regulation of neuronal proliferation. Therefore its loss-of-function or pathogenic missense mutations are likely to be causative of ASD.

Detecting copy-number variations in whole-exome sequencing data using the eXome Hidden Markov Model: an 'exome-first' approach.

Whole-exome sequencing (WES) is becoming a standard tool for detecting nucleotide changes, and determining whether WES data can be used for the detection of copy-number variations (CNVs) is of interest. To date, several algorithms have been developed for such analyses, although verification is needed to establish if they fit well for the appropriate purpose, depending on the characteristics of each algorithm. Here, we performed WES CNV analysis using the eXome Hidden Markov Model (XHMM). We validated its performance using 27 rare CNVs previously identified by microarray as positive controls, finding that the detection rate was 59%, or higher (89%) with three or more targets. XHMM can be effectively used, especially for the detection of >200 kb CNVs. XHMM may be useful for deletion breakpoint detection. Next, we applied XHMM to genetically unsolved patients, demonstrating successful identification of pathogenic CNVs: 1.5-1.9-Mb deletions involving NSD1 in patients with unknown overgrowth syndrome leading to the diagnosis of Sotos syndrome, and 6.4-Mb duplication involving MECP2 in affected brothers with late-onset spasm and progressive cerebral/cerebellar atrophy confirming the clinical suspect of MECP2 duplication syndrome. The possibility of an 'exome-first' approach for clinical genetic investigation may be considered to save the cost of multiple investigations.

De Novo 17q24.2-q24.3 microdeletion presenting with generalized hypertrichosis terminalis, gingival fibromatous hyperplasia, and distinctive facial features.

Generalized hypertrichosis is a feature of several genetic disorders, and the nosology of these entities is still provisional. Recent studies have implicated chromosome 17q24.2-q24.3 microdeletion and the reciprocal microduplication in a very rare form of congenital generalized hypertrichosis terminalis (CGHT) with or without gingival hyperplasia. Here, we report on a 5-year-old Egyptian girl born to consanguineous parents. The girl presented with CGHT and gingival hyperplasia for whom we performed detailed clinical, pathological, and molecular studies. The girl had coarse facies characterized by bilateral epicanthic folds, thick and abundant eyelashes, a broad nose, full cheeks, and lips that constituted the distinctive facial features for this syndrome. Biopsy of the gingiva showed epithelial marked acanthosis and hyperkeratosis with hyperplastic thick collagen bundles and dense fibrosis in the underlying tissues. Array analysis indicated a 17q24.2-q24.3 chromosomal microdeletion. We validated this microdeletion by real-time quantitative PCR and confirmed a perfect co-segregation of the disease phenotype within the family. In summary, this study indicates that 17q24.2-q24.3 microdeletion caused CGHT with gingival hyperplasia and distinctive facies, which should be differentiated from the autosomal recessive type that lacks the distinctive facies.

A de novo 1.4-Mb deletion at 21q22.11 in a boy with developmental delay.

Monosomy 21 is a very rare chromosomal abnormality. At least 45 patients with partial deletion involving 21q11 have been reported. Here, we report a Japanese boy who presented with pre- and postnatal growth delays, psychomotor developmental delay, microcephaly, and iris coloboma. Cytogenetic analysis revealed a de novo 1.4-Mb deletion at 21q22.11 containing 19 protein-coding RefSeq genes. We compared the clinical phenotypes between the present patient and 16 previously reported patients with a deleted region associated with postnatal growth delay and psychomotor developmental delay. Interestingly, ITSN1 was the only gene deleted or disrupted in all cases; this gene is known to be associated with intellectual disability. Microcephaly and brain structural abnormalities including polymicrogyria and agenesis/hypoplasia of the corpus callosum may also result from haploinsufficiency of ITSN1, highlighting its clinical significance for the neurological features of patients with monosomy 21.

Duplication of the NPHP1 gene in patients with autism spectrum disorder and normal intellectual ability: a case series.

Autism spectrum disorder is a neurodevelopmental disorder characterized by impairments in social interactions, reduced verbal communication abilities, stereotyped repetitive behaviors, and restricted interests. It is a complex condition caused by genetic and environmental factors; the high heritability of this disorder supports the presence of a significant genetic contribution. Many studies have suggested that copy-number variants contribute to the etiology of autism spectrum disorder. Recently, copy-number variants of the nephronophthisis 1 gene have been reported in patients with autism spectrum disorder. To the best of our knowledge, only six autism spectrum disorder cases with duplications of the nephronophthisis 1 gene have been reported. These patients exhibited intellectual dysfunction, including verbal dysfunction in one patient, below-average verbal intellectual ability in one patient, and intellectual disability in four patients. In this study, we identified nephronophthisis 1 duplications in two unrelated Japanese patients with autism spectrum disorder using a high-resolution single-nucleotide polymorphism array. This report is the first to describe a nephronophthisis 1 duplication in an autism spectrum disorder patient with an average verbal intelligence quotient and an average performance intelligence quotient. However, the second autism spectrum disorder patient with a nephronophthisis 1 duplication had a below-average performance intelligence quotient. Neither patient exhibited physical dysfunction, motor developmental delay, or neurological abnormalities. This study supports the clinical observation of nephronophthisis 1 duplication in autism spectrum disorder cases and might contribute to our understanding of the clinical phenotype that arises from this duplication.

Co-occurrence of 22q11 deletion syndrome and HDR syndrome.

22q11 deletion syndrome is one of the most common chromosomal deletion syndromes and is usually caused by a 1.5-3.0 Mb deletion at chromosome 22q11.2. It is characterized by hypocalcemia resulting from hypoplasia of the parathyroid glands, hypoplasia of the thymus, and defects of the cardiac outflow tract. We encountered a Japanese boy presenting with an unusually severe phenotype of 22q11 deletion syndrome, including progressive renal failure and severe intellectual disabilities. Diagnostic testing using fluorescent in situ hybridization revealed deletion of the 22q11 region, but this did not explain the additional complications. Copy number analysis was therefore performed using whole genome single nucleotide polymorphism (SNP) assay, which identified an additional de novo deletion at 10p14. This region is the locus for hypoparathyroidism, deafness, and renal dysplasia (HDR) syndrome caused by haploinsufficiency of GATA3. Together, these two syndromes sufficiently explain the patient's phenotype. This is the first known case report of the co-occurrence of 22q11 deletion syndrome and HDR syndrome. As the two syndromes overlap clinically, this study indicates the importance of carrying out careful clinical and genetic assessment of patients with atypical clinical phenotypes or unique complications. Unbiased genetic analysis using whole genome copy number SNP arrays is especially useful for detecting such rare double mutations.

Molecular diagnosis of 405 individuals with autism spectrum disorder.

Autism spectrum disorder (ASD) is caused by combined genetic and environmental factors. Genetic heritability in ASD is estimated as 60-90%, and genetic investigations have revealed many monogenic factors. We analyzed 405 patients with ASD using family-based exome sequencing to detect disease-causing single-nucleotide variants (SNVs), small insertions and deletions (indels), and copy number variations (CNVs) for molecular diagnoses. All candidate variants were validated by Sanger sequencing or quantitative polymerase chain reaction and were evaluated using the American College of Medical Genetics and Genomics/Association for Molecular Pathology guidelines for molecular diagnosis. We identified 55 disease-causing SNVs/indels in 53 affected individuals and 13 disease-causing CNVs in 13 affected individuals, achieving a molecular diagnosis in 66 of 405 affected individuals (16.3%). Among the 55 disease-causing SNVs/indels, 51 occurred de novo, 2 were compound heterozygous (in one patient), and 2 were X-linked hemizygous variants inherited from unaffected mothers. The molecular diagnosis rate in females was significantly higher than that in males. We analyzed affected sibling cases of 24 quads and 2 quintets, but only one pair of siblings shared an identical pathogenic variant. Notably, there was a higher molecular diagnostic rate in simplex cases than in multiplex families. Our simulation indicated that the diagnostic yield is increasing by 0.63% (range 0-2.5%) per year. Based on our simple simulation, diagnostic yield is improving over time. Thus, periodical reevaluation of ES data should be strongly encouraged in undiagnosed ASD patients.

Case Report: Anti-MOG Antibody Seroconversion Accompanied by Dimethyl Fumarate Treatment.

Here we report three cases of anti-myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) mimicking multiple sclerosis in which seropositivity for anti-MOG antibodies occurred during disease-modifying drug dimethyl fumarate (DMF) treatment. These patients developed relapses with anti-MOG antibody seroconversion after switching from fingolimod or steroid pulse therapy to DMF, which was associated with peripheral lymphocyte recovery. MOGAD is considered a humoral immune disease, and DMF reportedly enhances Th2-skewed humoral immune activity. Therefore, we suggest that DMF, but not fingolimod, may exacerbate humoral immune imbalance and enhance autoantibody production, leading to aggravation of MOGAD.

SGTA associates with intracellular aggregates in neurodegenerative diseases.

Intracellular aggregates are a common pathological hallmark of neurodegenerative diseases such as polyglutamine (polyQ) diseases, amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), and multiple system atrophy (MSA). Aggregates are mainly formed by aberrant disease-specific proteins and are accompanied by accumulation of other aggregate-interacting proteins. Although aggregate-interacting proteins have been considered to modulate the formation of aggregates and to be involved in molecular mechanisms of disease progression, the components of aggregate-interacting proteins remain unknown. In this study, we showed that small glutamine-rich tetratricopeptide repeat-containing protein alfa (SGTA) is an aggregate-interacting protein in neurodegenerative diseases. Immunohistochemistry showed that SGTA interacted with intracellular aggregates in Huntington disease (HD) cell models and neurons of HD model mice. We also revealed that SGTA colocalized with intracellular aggregates in postmortem brains of patients with polyQ diseases including spinocerebellar ataxia (SCA)1, SCA2, SCA3, and dentatorubral-pallidoluysian atrophy. In addition, SGTA colocalized with glial cytoplasmic inclusions in the brains of MSA patients, whereas no accumulation of SGTA was observed in neurons of PD and ALS patients. In vitro study showed that SGTA bound to polyQ aggregates through its C-terminal domain and SGTA overexpression reduced intracellular aggregates. These results suggest that SGTA may play a role in the formation of aggregates and may act as potential modifier of molecular pathological mechanisms of polyQ diseases and MSA.

Non-traumatic Acute Epidural Hematoma in Multiple Sclerosis Treated With Fingolimod.

Fingolimod acts as a functional antagonist of the sphingosine-1-phosphate receptor and is widely used for relapsing-remitting multiple sclerosis (MS). Here we report the first case of non-traumatic acute epidural hematoma in a relapsing-remitting MS patient treated with fingolimod. Fingolimod might increase the risk of hemorrhage by enhancing vasospasm and causing vascular disruption. Switching fingolimod to other disease-modifying drugs, including dimethyl fumarate, should be considered when non-traumatic hemorrhage is observed in MS patients.