Dystonia and Parkinsonism in COA7-related disorders: expanding the phenotypic spectrum.

BACKGROUND AND OBJECTIVE: Biallelic mutations in the COA7 gene have been associated with spinocerebellar ataxia with axonal neuropathy type 3 (SCAN3), and a notable clinical diversity has been observed. We aim to identify the genetic and phenotypic spectrum of COA7-related disorders. METHODS: We conducted comprehensive genetic analyses on the COA7 gene within a large group of Japanese patients clinically diagnosed with inherited peripheral neuropathy or cerebellar ataxia. RESULTS: In addition to our original report, which involved four patients until 2018, we identified biallelic variants of the COA7 gene in another three unrelated patients, and the variants were c.17A > G (p.D6G), c.115C > T (p.R39W), and c.449G > A (p.C150Y; novel). Patient 1 presented with an infantile-onset generalized dystonia without cerebellar ataxia. Despite experiencing an initial transient positive response to levodopa and deep brain stimulation, he became bedridden by the age of 19. Patient 2 presented with cerebellar ataxia, neuropathy, as well as parkinsonism, and showed a slight improvement upon levodopa administration. Dopamine transporter SPECT showed decreased uptake in the bilateral putamen in both patients. Patient 3 exhibited severe muscle weakness, respiratory failure, and feeding difficulties. A haplotype analysis of the mutation hotspot in Japan, c.17A > G (p.D6G), uncovered a common haplotype block. CONCLUSION: COA7-related disorders typically encompass a spectrum of conditions characterized by a variety of major (cerebellar ataxia and axonal polyneuropathy) and minor (leukoencephalopathy, dystonia, and parkinsonism) symptoms, but may also display a dystonia-predominant phenotype. We propose that COA7 should be considered as a new causative gene for infancy-onset generalized dystonia, and COA7 gene screening is recommended for patients with unexplained dysfunctions of the central and peripheral nervous systems.

Cerebellar Hypoperfusion in Two Patients with Cornelia de Lange Syndrome with Novel NIPBL Variants.

Introduction: Cornelia de Lange syndrome (CdLS) is a rare congenital malformation characterized by distinctive facial features, short stature, and limb defects. In addition, half of the patients with CdLS exhibit repetitive self-injurious behaviors (SIBs) related to intellectual disability with autistic traits. CdLS is caused by pathogenic variants of genes encoding the cohesin complex pathway, with 70% of these variants identified in the nipped-B-like (NIPBL) gene. Case Presentation: We report 2 patients with CdLS who exhibited repetitive SIBs. Patient 1, a 40-year-old male, carried a novel heterozygous duplication variant, c.1458dup, p.(Glu487*), in exon 9 of the NIPBL gene. Patient 2, a 49-year-old female, carried a novel heterozygous insertion variant, c.1751_1752ins[A;1652_1751], p.(Asp584Glufs*8), in exon 10 of the NIPBL gene. These variants were predicted to confer loss of function to the protein because of a premature stop codon. In both patients, single-photon emission computed tomography using N-isopropyl-p-[123I] iodoamphetamine (IMP-SPECT) revealed diffuse hypoperfusion in the cerebellum. Discussion: This report identified 2 novel pathogenic variants in the NIPBL gene and the relationship between SIBs and cerebellar hypoperfusion in patients with CdLS. The cerebellar hypoperfusion might have been caused by the dysfunction of the cohesin complex via the downregulation of the NIPBL gene products. Further studies should be conducted to elucidate the contribution of the NIPBL gene to the development of the cerebello-cerebral cortical circuits associated with behavioral disorders.

Whole-Exome Sequencing Identified a Novel DYRK1A Variant in a Patient With Intellectual Developmental Disorder, Autosomal Dominant 7.

Intellectual developmental disorder, autosomal dominant 7 (MRD7; OMIM 614104) is a rare disease characterized by microcephaly, intellectual disability, speech delay, feeding difficulties, and facial dysmorphisms. This disorder is caused by pathogenic/likely pathogenic variants of the DYRK1A gene, which encodes dual-specificity tyrosine-phosphorylation-regulated kinase 1A. Here, we report a case of MRD7 that was diagnosed using Face2Gene and whole-exome sequencing (WES). A 22-year-old man presented with microcephaly, intellectual disability, slender body, long slender fingers, and facial dysmorphisms. He was previously diagnosed with Cornelia de Lange syndrome (CdLS) at four years of age. However, his CdLS clinical diagnostic score was low at 22 years of age. The Face2Gene application introduced several candidate diseases including MRD7. Finally, by utilizing WES and Sanger sequencing analysis of cloned cDNA, we identified a novel heterozygous duplication variant (c.848dup, p.(Asn283LysfsTer6)) in the DYRK1A gene, which introduces a premature stop codon. This report provides more information about the phenotypic spectrum of a young adult patient with MRD7. Face2Gene helped us introduce candidate diseases of the patient. Registering further genetically confirmed cases with MRD7 will improve the accuracy of the diagnostic recommendations in Face2Gene. Moreover, WES is a powerful tool for diagnosing rare genetic diseases, such as MRD7.

Dyggve-Melchior-Clausen Syndrome Caused by a Novel Frameshift Variant in a Japanese Patient.

Introduction: Dyggve-Melchior-Clausen syndrome (DMC) is a rare autosomal recessive spondyloepimetaphyseal dysplasia characterized by short stature, microcephaly, intellectual disability, and coarse face. This disorder is caused by pathogenic/likely pathogenic variants of the DYM gene which encodes dymeclin. Case Presentation: Herein, we report a 60-year-old Japanese man who was born to consanguineous parents. He presented with abdominal distention and rectal prolapse in addition to the common features of DMC. We identified a novel homozygous frameshift variant [c.1670delT, p.(Leu557Argfs*20)] in the DYM gene, which introduces a premature stop codon. Histological analysis revealed disarrangement of actin filaments in cultured fibroblasts. Discussion: To the best of our knowledge, this is the first Japanese case of DMC with a confirmed variant in the DYM gene. This report provides more information about the geographic distribution and phenotypic spectrum of DMC. Moreover, it presents a novel DYM variant and insights about DMC pathology that may be associated with the disarrangement of actin filaments.

Frontal Hypoperfusion and the Effectiveness of Perampanel in Long-Lived Patient with Lafora Disease.

We report a long-lived patient with Lafora disease (LD). A 34-year-old woman experienced onset of seizures at the age of 11 years. She was bedridden in her early twenties due to frequent generalized tonic-clonic seizures, myoclonus, and progressive mental deterioration. Her seizures occurred all the time despite administration of multiple anticonvulsants at high doses. At the age of 31, she started perampanel, which resulted in reduction of anticonvulsants after her visible myoclonus and convulsions disappeared. Brain magnetic resonance imaging showed marked cerebral and cerebellar atrophy, and single-photon emission computed tomography using N-isopropyl-p-[123I] iodoamphetamine (IMP-SPECT) revealed significant hypoperfusion of the frontal lobe and cerebellum. We identified a W219R homozygous mutation in exon 1 of the NHLRC1 gene. Because perampanel may not only control seizures but also prevent mental deterioration in LD, we propose that perampanel should be administered from the early stage of LD.

Anti-N-Methyl-D-Aspartate Receptor Encephalitis with Decrease in Blood Flow in Cerebellum.

In anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis, progressive cerebellar atrophy potentially leads to severe sequelae. We encountered a patient with anti-NMDAR antibody encephalitis who showed a decrease of blood flow in the cerebellum. A 15-year-old girl presented with consciousness disturbance. Influenza encephalopathy was suspected, and she was treated with glucocorticoid pulse therapy, high-dose intravenous immunoglobulins, and plasma exchange sequentially. She subsequently underwent left oophorectomy due to the presence of anti-NMDAR antibodies and a left ovarian teratoma. In spite of the surgery, her neuropsychiatric symptoms persisted, and she recovered slowly after the introduction of oral methotrexate (MTX). Sequential cerebral blood flow monitoring with single-photon emission computed tomography showed marked cerebellar hypoperfusion. Although mild impairments including working memory and verbal fluency persisted, she eventually returned to high school 3 years after onset. Profound cerebellar hypoperfusion including lobules VI and VII may be the reason for her working memory impairment and speaking problems. Oral MTX may be a promising alternative treatment for some refractory cases of anti-NMDAR encephalitis.

The Effectiveness of Perampanel for Myoclonic Seizures in Down Syndrome with Isodicentric Chromosome 21.

Epileptic seizures are common in the elderly Down syndrome population. We encountered a patient with Down syndrome in whom karyotyping showed the rare isodicentric chromosome 21 and who suffered from myoclonic seizures. A 52-year-old woman with Down syndrome experienced sudden onset of drowsiness and frequent myoclonic jerks in the upper body. Video-EEG recordings demonstrated generalized polyspike-wave discharges consistent with myoclonic jerks, which were exacerbated by photo-stimulation. Her myoclonus completely resolved with perampanel administration. Perampanel was effective for myoclonic seizures in our patient. We suggest that perampanel is an option as first-line therapy for epilepsy and myoclonus in elderly Down syndrome patients.

A case of female adrenoleukodystrophy carrier with insidious neurogenic bladder.

A 65-year-old woman with mutation of the ABCD1 gene for adrenoleukodystrophy (ALD) was admitted to our hospital with a urinary tract infection. Abdominal computed tomography showed dilation of the urinary tract. Although she had noticed pollakisuria since her forties, she had not been followed up by any medical institutions until we diagnosed her as a female carrier with ALD. ALD is an X-linked pattern of inheritance that typically affects males, but many female carriers actually present slowly progressive myelopathy and neuropathy. Therefore, it is important to identify female carriers with ALD and treat them at the earliest stage possible.

Partial reduced Pi transport function of PiT-2 might not be sufficient to induce brain calcification of idiopathic basal ganglia calcification.

Idiopathic basal ganglia calcification (IBGC) is a rare intractable disease characterized by abnormal mineral deposits, including mostly calcium in the basal ganglia, thalamus, and cerebellum. SLC20A2 is encoding the phosphate transporter PiT-2 and was identified in 2012 as the causative gene of familial IBGC. In this study, we investigated functionally two novel SLC20A2 variants (c.680C > T, c.1487G > A) and two SLC20A2 variants (c.82G > A, c.358G > C) previously reported from patients with IBGC. We evaluated the function of variant PiT-2 using stable cell lines. While inorganic phosphate (Pi) transport activity was abolished in the cells with c.82G > A, c.358G > C, and c.1487G > A variants, activity was maintained at 27.8% of the reference level in cells with the c.680C > T variant. Surprisingly, the c.680C > T variant had been discovered by chance in healthy members of an IBGC family, suggesting that partial preservation of Pi transport activity may avoid the onset of IBGC. In addition, we confirmed that PiT-2 variants could be translocated into the cell membrane to the same extent as PiT-2 wild type. In conclusion, we investigated the PiT-2 dysfunction of four SLC20A2 variants and suggested that a partial reduced Pi transport function of PiT-2 might not be sufficient to induce brain calcification of IBGC.

Medical Attitudes Survey for Female Dystrophinopathy Carriers in Japan.

Objective This study attempted to clarify the current status of female dystrophinopathy carriers, including the numbers of patients, the status of genetic screening, the status of counseling, physicians' understanding, and barriers to registration. Methods We sent out questionnaires to 402 physicians registered in the Remudy dystrophinopathy registry. The total number of responses received was 130 (response rate: 32%). Result In total, 1,212 cases of Duchenne muscular dystrophy, 365 cases of Becker muscular dystrophy, and 132 cases of female dystrophinopathy with a confirmed genetic mutation were encountered, and genetic testing was performed in the mother in 137, 23, and 12 cases, respectively. With respect to the risk of the onset of health problems, 25% of physicians always explained, 29% usually explained, 29% sometimes explained, and 13% never explained the risk to the mothers and female siblings of dystrophinopathy patients. The most common reason for not explaining the risk was a lack of knowledge/information. Thirty-five percent were familiar with the guidelines for testing the heart function of carriers. Conclusion Fewer mothers of dystrophinopathy patients have undergone genetic testing in Japan than in other countries. A significant portion of doctors did not explain the risks of health problems due to a lack of knowledge. We hope this survey will lead to an increased discussion of female dystrophinopathy patients.

Questionnaire survey on recruitment for Japanese Neurology Society.

Many claim that they do not have enough neurologists in Japan, but supply and demand of neurologists remains to be analyzed. To investigate the recruitment for the Japanese Society of Neurology (JSN), the subcommittee of JSN for education performed a questionnaire-based survey in 80 medical universities and 271 board-certified education facilities throughout Japan. The response rate to the questionnaire was 77.5% in medical universities and 42.4% in education facilities. It was shown that each department of neurology in university recruits average 2.2 doctors, while they supposed that more than 4 doctors to be recruited every year. The questionnaire survey included what measures JSN should take in order to promote recruitment for JSN.

Survey on genetic counseling and health management for symptomatic and asymptomatic female dystrophinopathy carriers in Japan today.

To clarify the current status of genetic counseling and health monitoring for symptomatic and asymptomatic female carriers of dystrophinopathy (Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD)), we sent out questionnaires to 104 member institutions of The Japan's National Liaison Council for Clinical Sections of Medical Genetics, and responses were received from 51 institutions. Between April 2013 and March 2014, 57 carriers at 21 institutions received genetic counseling, and 37 carriers at 15 institutions underwent genetic screening for DMD/BMD mutations. At the 23 institutions that gave genetic counseling, 20 (87%) informed carriers of possible health problems, 14 (61%) informed carriers of cardiomyopathy and heart failure, and 14 (61%) advised carriers about regular medical checkups. Evidence based on accurate and up-to-date epidemiological studies of female carriers is needed and should be widely shared with the families, medical providers, and society.

[Actual state and problems in neurology training in medical schools].

To investigate the need for pre- and post-graduate education for neurologists, the subcommittee of the Japanese Society of Neurology for education performed a questionnaire-based survey in 80 medical universities throughout Japan. The response rate to the questionnaire was 82.5%. Textbooks for lectures for medical students were used in only 22.7% of those universities. If the Japanese Society of Neurology (JSN) made a standard text, 77.8% of universities would like to use it. Most of the training programs for residents were compatible with the minimum requirements of the JSN. Just 66.7% of those training programs were completed in their own institute, and 77.3% of universities required help from the JSN.

[Actual state and problems in neurology training at hospital].

To evaluate postgraduate neurological education, a questionnaire-based survey regarding junior and senior doctor-in-training and the Board Certification Examination in Neurology was carried out on the training supervisors of 690 insitutes, excluding 80 university hospitals. The institutes included 243 teaching hospitals, 326 semi-teaching hospitals and 121 education-associated institutes authorized by the Japanese Society of Neurology (JSN). The results were obtained from 388 institutes, and the response rate was 56.2%. The percentage of junior doctors-in-training that received training in neurology was 68.6% (the average of 2.1 months during 2 years). More than half of the institutes did not have any teaching programs for junior doctors-in-training who did not train in neurology. In senior doctors-in-training, the number of senior doctors-in-trainings per year per institute was 0.44 and was only able to experience limited types of disorders. Also, many institutes could not achieve training goals by the institutes themselves (56%). The problems were due to lack of teaching staffs and manpower, and there were many requests to the Society regarding training methods. As for the Board Certification Examination in Neurology by the Society, it was revealed that there were small number of candidates per year per institute, and over half of institutes could not sufficiently teach and support them. Most requests to the Society were regarding teaching seminars and hands-on courses, and some institutes asked small group meetings for arts and techniques of neurology to be held the Regional Society. In conclusion, there are problems that cannot be solved by individual institutes alone, and we need procedures for postgraduate training in neurology that is organized by the Regional and JSN working as the central organization.

[Actual state and problems in neurology training at graduate school].

To understand the status of postgraduate education in neurology in Japan, the Committee for the Education of Undergraduate Students and Junior Residents within the Japanese Society of Neurology investigated the four-year trend at 80 medical schools from 2009 to 2012. The mean number of new students to each postgraduate school increased from 1.24 to 1.67 during these four years. After training clinical neurology, more than half of the neurological residents entered the postgraduate schools. Students in the postgraduate schools seemed to be researching major neurological diseases using various methods at each neurology laboratory. However, some problems were suggested. First, the mean number of newcomers to the neurology departments of the universities decreased gradually from 2.29/year to 1.96/year. Second, many of the postgraduate students were working in patient services at university hospitals or as part-time workers at other hospitals, and may not have sufficient time for their research projects. Third, many of the postgraduate students were carrying out research at each affiliated department of neurology, and may not have the opportunity to work in laboratories specializing in basic science. Finally, there may not be sufficient opportunities for further research at other laboratories in Japan or overseas after they finished their work at postgraduate school.

A nationwide survey of Aicardi-Goutières syndrome patients identifies a strong association between dominant TREX1 mutations and chilblain lesions: Japanese cohort study.

OBJECTIVES: Aicardi-Goutières syndrome (AGS) is a rare, genetically determined, early onset progressive encephalopathy associated with autoimmune manifestations. AGS is usually inherited in an autosomal recessive manner. The disease is rare, therefore the clinical manifestations and genotype-phenotype correlations, particularly with regard to autoimmune diseases, are still unclear. Here we performed a nationwide survey of AGS patients in Japan and analysed the genetic and clinical data. METHODS: Patients were recruited via questionnaires sent to paediatric or adult neurologists in Japanese hospitals and institutions. Genetic analysis was performed and clinical data were collected. RESULTS: Fourteen AGS patients were identified from 13 families; 10 harboured genetic mutations. Three patients harboured dominant-type TREX1 mutations. These included two de novo cases: one caused by a novel heterozygous p.His195Tyr mutation and the other by a novel somatic mosaicism resulting in a p.Asp200Asn mutation. Chilblain lesions were observed in all patients harbouring dominant-type TREX1 mutations. All three patients harbouring SAMHD1 mutations were diagnosed with autoimmune diseases, two with SLE and one with SS. The latter is the first reported case. CONCLUSION: This study is the first to report a nationwide AGS survey, which identified more patients with sporadic AGS carrying de novo dominant-type TREX1 mutations than expected. There was a strong association between the dominant-type TREX1 mutations and chilblain lesions, and between SAMHD1 mutations and autoimmunity. These findings suggest that rheumatologists should pay attention to possible sporadic AGS cases presenting with neurological disorders and autoimmune manifestations.

Clinicopathological features of neuropathy associated with lymphoma.

Lymphoma causes various neurological manifestations that might affect any part of the nervous system and occur at any stage of the disease. The peripheral nervous system is one of the major constituents of the neurological involvement of lymphoma. In this study we characterized the clinical, electrophysiological and histopathological features of 32 patients with neuropathy associated with non-Hodgkin's lymphoma that were unrelated to complications resulting from treatment for lymphoma. Nine patients had pathologically-proven neurolymphomatosis with direct invasion of lymphoma cells into the peripheral nervous system. These patients showed lymphomatous cell invasion that was more prominent in the proximal portions of the nerve trunk and that induced demyelination without macrophage invasion and subsequent axonal degeneration in the portion distal from the demyelination site. Six other patients were also considered to have neurolymphomatosis because these patients showed positive signals along the peripheral nerve on fluorodeoxyglucose positron emission tomography imaging. Spontaneous pain can significantly disrupt daily activities, as frequently reported in patients diagnosed with neurolymphomatosis. In contrast, five patients were considered to have paraneoplastic neuropathy because primary peripheral nerve lesions were observed without the invasion of lymphomatous cells, with three patients showing features compatible with chronic inflammatory demyelinating polyneuropathy, one patient showing sensory ganglionopathy, and one patient showing vasculitic neuropathy. Of the other 12 patients, 10 presented with multiple mononeuropathies. These patients showed clinical and electrophysiological features similar to those of neurolymphomatosis rather than paraneoplastic neuropathy. Electrophysiological findings suggestive of demyelination were frequently observed, even in patients with neurolymphomatosis. Eleven of the 32 patients, including five patients with neurolymphomatosis, fulfilled the European Federation of Neurological Societies/Peripheral Nerve Society electrodiagnostic criteria of definite chronic inflammatory demyelinating polyneuropathy. Some of these patients, even those with neurolymphomatosis, responded initially to immunomodulatory treatments, including the administration of intravenous immunoglobulin and steroids. Patients with lymphoma exhibit various neuropathic patterns, but neurolymphomatosis is the major cause of neuropathy. Misdiagnoses of neurolymphomatosis as chronic inflammatory demyelinating polyneuropathy are frequent due to a presence of a demyelinating pattern and the initial response to immunomodulatory treatments. The possibility of the concomitance of lymphoma should be considered in various types of neuropathy, even if the diagnostic criteria of chronic inflammatory demyelinating polyneuropathy are met, particularly in patients complaining of pain.

Phosphorylated Syk expression is enhanced in Nasu-Hakola disease brains.

Nasu-Hakola disease (NHD) is a rare autosomal recessive disorder, characterized by progressive presenile dementia and formation of multifocal bone cysts, caused by a loss-of-function mutation of DNAX-activation protein 12 (DAP12) or triggering receptor expressed on myeloid cells 2 (TREM2). TREM2 and DAP12 constitute a receptor/adaptor complex on myeloid cells. The post-receptor signals are transmitted via rapid phosphorylation of the immunoreceptor tyrosine-based activating motif (ITAM) of DAP12, mediated by Src protein tyrosine kinases, followed by binding of phosphorylated ITAM to Src homology 2 (SH2) domains of spleen tyrosine kinase (Syk), resulting in autophosphorylation of the activation loop of Syk. To elucidate the molecular mechanism underlying the pathogenesis of NHD, we investigated Syk expression and activation in the frontal cortex and the hippocampus of three NHD and eight control brains by immunohistochemistry. In NHD brains, the majority of neurons expressed intense immunoreactivities for Syk and Y525/Y526-phosphorylated Syk (pSyk) chiefly located in the cytoplasm, while more limited populations of neurons expressed Src. The levels of pSyk expression were elevated significantly in NHD brains compared with control brains. In both NHD and control brains, substantial populations of microglia and macrophages expressed pSyk, while the great majority of reactive astrocytes and myelinating oligodendrocytes did not express pSyk, Syk or Src. These observations indicate that neuronal expression of pSyk was greatly enhanced in the cerebral cortex and the hippocampus of NHD brains, possibly via non-TREM2/DAP12 signaling pathways involved in Syk activation.

A mutation in the immunoproteasome subunit PSMB8 causes autoinflammation and lipodystrophy in humans.

Proteasomes are multisubunit proteases that play a critical role in maintaining cellular function through the selective degradation of ubiquitinated proteins. When 3 additional ß subunits, expression of which is induced by IFN-γ, are substituted for their constitutively expressed counterparts, the structure is converted to an immunoproteasome. However, the underlying roles of immunoproteasomes in human diseases are poorly understood. Using exome analysis, we found a homozygous missense mutation (G197V) in immunoproteasome subunit, ß type 8 (PSMB8), which encodes one of the ß subunits induced by IFN-γ in patients from 2 consanguineous families. Patients bearing this mutation suffered from autoinflammatory responses that included recurrent fever and nodular erythema together with lipodystrophy. This mutation increased assembly intermediates of immunoproteasomes, resulting in decreased proteasome function and ubiquitin-coupled protein accumulation in the patient's tissues. In the patient's skin and B cells, IL-6 was highly expressed, and there was reduced expression of PSMB8. Downregulation of PSMB8 inhibited the differentiation of murine and human adipocytes in vitro, and injection of siRNA against Psmb8 in mouse skin reduced adipocyte tissue volume. These findings identify PSMB8 as an essential component and regulator not only of inflammation, but also of adipocyte differentiation, and indicate that immunoproteasomes have pleiotropic functions in maintaining the homeostasis of a variety of cell types.