Publications by authors named "Kaori Aiba"

9 Publications

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Clinical and molecular genetic characterization of two female patients harboring the Xq27.3q28 deletion with different ratios of X chromosome inactivation.

Hum Mutat 2020 08 19;41(8):1447-1460. Epub 2020 Jun 19.

Department of Genetics, Institute for Developmental Research, Aichi Developmental Disability Center, Kasugai, Aichi, Japan.

A heterozygous deletion at Xq27.3q28 including FMR1, AFF2, and IDS causing intellectual disability and characteristic facial features is very rare in females, with only 10 patients having been reported. Here, we examined two female patients with different clinical features harboring the Xq27.3q28 deletion and determined the chromosomal breakpoints. Moreover, we assessed the X chromosome inactivation (XCI) in peripheral blood from both patients. Both patients had an almost overlapping deletion at Xq27.3q28, however, the more severe patient (Patient 1) showed skewed XCI of the normal X chromosome (79:21) whereas the milder patient (Patient 2) showed random XCI. Therefore, deletion at Xq27.3q28 critically affected brain development, and the ratio of XCI of the normal X chromosome greatly affected the clinical characteristics of patients with deletion at Xq27.3q28. As the chromosomal breakpoints were determined, we analyzed a change in chromatin domains termed topologically associated domains (TADs) using published Hi-C data on the Xq27.3q28 region, and found that only patient 1 had a possibility of a drastic change in TADs. The altered chromatin topologies on the Xq27.3q28 region might affect the clinical features of patient 1 by changing the expression of genes just outside the deletion and/or the XCI establishment during embryogenesis resulting in skewed XCI.
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http://dx.doi.org/10.1002/humu.24058DOI Listing
August 2020

Nusinersen helps restore walking ability in childhood spinal muscular atrophy.

Pediatr Int 2019 Jul 9;61(7):728-729. Epub 2019 Jul 9.

Department of Community Medicine and Social Healthcare Science, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan.

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http://dx.doi.org/10.1111/ped.13867DOI Listing
July 2019

Comprehensive analysis of coding variants highlights genetic complexity in developmental and epileptic encephalopathy.

Nat Commun 2019 06 7;10(1):2506. Epub 2019 Jun 7.

Department of Human Genetics, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004, Japan.

Although there are many known Mendelian genes linked to epileptic or developmental and epileptic encephalopathy (EE/DEE), its genetic architecture is not fully explained. Here, we address this incompleteness by analyzing exomes of 743 EE/DEE cases and 2366 controls. We observe that damaging ultra-rare variants (dURVs) unique to an individual are significantly overrepresented in EE/DEE, both in known EE/DEE genes and the other non-EE/DEE genes. Importantly, enrichment of dURVs in non-EE/DEE genes is significant, even in the subset of cases with diagnostic dURVs (P = 0.000215), suggesting oligogenic contribution of non-EE/DEE gene dURVs. Gene-based analysis identifies exome-wide significant (P = 2.04 × 10) enrichment of damaging de novo mutations in NF1, a gene primarily linked to neurofibromatosis, in infantile spasm. Together with accumulating evidence for roles of oligogenic or modifier variants in severe neurodevelopmental disorders, our results highlight genetic complexity in EE/DEE, and indicate that EE/DEE is not an aggregate of simple Mendelian disorders.
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http://dx.doi.org/10.1038/s41467-019-10482-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6555845PMC
June 2019

variants in and cause neurodevelopmental disorders.

Ann Clin Transl Neurol 2018 03 29;5(3):280-296. Epub 2018 Jan 29.

Department of Biochemistry Hamamatsu University School of Medicine 1-20-1 Handayama, Higashi-ku Hamamatsu 431-3192 Japan.

Objective: () and () isoforms of Calcium/calmodulin-dependent protein kinase II (CaMKII) play a pivotal role in neuronal plasticity and in learning and memory processes in the brain. Here, we explore the possible involvement of - and -CaMKII variants in neurodevelopmental disorders.

Methods: Whole-exome sequencing was performed for 976 individuals with intellectual disability, developmental delay, and epilepsy. The effect of and variants on CaMKII structure and firing of neurons was evaluated by computational structural analysis, immunoblotting, and electrophysiological analysis.

Results: We identified a total of five de novo and variants in three and two individuals, respectively. Seizures were common to three individuals with variants. Using a minigene splicing assay, we demonstrated that a splice site variant caused skipping of exon 11 leading to an in-frame deletion of the regulatory segment of CaMKII . By structural analysis, four missense variants are predicted to impair the interaction between the kinase domain and the regulatory segment responsible for the autoinhibition of its kinase activity. The Thr286/Thr287 phosphorylation as a result of release from autoinhibition was increased in three mutants when the mutants were stably expressed in Neuro-2a neuroblastoma cells. Expression of a CaMKII mutant in primary hippocampal neurons significantly increased A-type K currents, which facilitated spike repolarization of single action potentials.

Interpretation: Our data highlight the importance of CaMKII and CaMKII and their autoinhibitory regulation in human brain function, and suggest the enhancement of A-type K currents as a possible pathophysiological basis.
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http://dx.doi.org/10.1002/acn3.528DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5846454PMC
March 2018

A case report of mitochondrial respiratory chain disorder in the neonatal period for which home mechanical ventilation was introduced.

No To Hattatsu 2017 Jan;49(1):37-41

We report the case of a patient born with extreme muscle hypotonia, respiratory failure, and slightly elevated serum levels of lactic acid. Histochemical examination and mitochondrial respiratory chain enzyme activities of a muscle biopsy specimen revealed reduced activities of complexes Ⅰ, Ⅲ, and Ⅳ, diagnostic of mitochondrial respiratory chain disorder. Hypertrophic cardiomyopathy developed as a complication and additional therapy was administered at 3 months after birth. He was able to be discharged to home on applied home mechanical ventilation with tracheotomy at 1 year old. The patient survived until 4 years and 10 months of age, upon which he died of bronchitis. Early-onset mitochondrial respiratory chain disorder shows very poor prognosis and long-term survival has not been reported. Prompt assessment of mitochondrial respiratory chain enzyme activities is necessary for the diagnosis of congenital nonspecific multiple-organ failure, and early intervention may achieve better prognosis for mitochondrial respiratory chain disorder.
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January 2017

Clinical, biochemical and metabolic characterisation of a mild form of human short-chain enoyl-CoA hydratase deficiency: significance of increased N-acetyl-S-(2-carboxypropyl)cysteine excretion.

J Med Genet 2015 Oct 6;52(10):691-8. Epub 2015 Aug 6.

Department of Genetics, Institute for Developmental Research, Aichi Human Service Center, Kasugai, Aichi, Japan.

Background: Short-chain enoyl-CoA hydratase-ECHS1-catalyses many metabolic pathways, including mitochondrial short-chain fatty acid β-oxidation and branched-chain amino acid catabolic pathways; however, the metabolic products essential for the diagnosis of ECHS1 deficiency have not yet been determined. The objective of this report is to characterise ECHS1 and a mild form of its deficiency biochemically, and to determine the candidate metabolic product that can be efficiently used for neonatal diagnosis.

Methods: We conducted a detailed clinical, molecular genetics, biochemical and metabolic analysis of sibling patients with ECHS1 deficiency. Moreover, we purified human ECHS1, and determined the substrate specificity of ECHS1 for five substrates via different metabolic pathways.

Results: Human ECHS1 catalyses the hydration of five substrates via different metabolic pathways, with the highest specificity for crotonyl-CoA and the lowest specificity for tiglyl-CoA. The patients had relatively high (∼7%) residual ECHS1 enzyme activity for crotonyl-CoA and methacrylyl-CoA caused by the compound heterozygous mutations (c.176A>G, (p.N59S) and c.413C>T, (p.A138V)) with normal mitochondrial complex I-IV activities. Affected patients excrete large amounts of N-acetyl-S-(2-carboxypropyl)cysteine, a metabolite of methacrylyl-CoA.

Conclusions: Laboratory data and clinical features demonstrated that the patients have a mild form of ECHS1 deficiency harbouring defective valine catabolic and β-oxidation pathways. N-Acetyl-S-(2-carboxypropyl) cysteine level was markedly high in the urine of the patients, and therefore, N-acetyl-S-(2-carboxypropyl)cysteine was regarded as a candidate metabolite for the diagnosis of ECHS1 deficiency. This metabolite is not part of current routine metabolic screening protocols, and its inclusion, therefore, holds immense potential in accurate diagnosis.
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http://dx.doi.org/10.1136/jmedgenet-2015-103231DOI Listing
October 2015

Three patients manifesting early infantile epileptic spasms associated with 2q24.3 microduplications.

Brain Dev 2015 Oct 3;37(9):874-9. Epub 2015 Apr 3.

Institute of Medical Genetics, Tokyo Women's Medical University, Tokyo, Japan; Tokyo Women's Medical University Institute for Integrated Medical Sciences, Tokyo, Japan.

Background: Recent development of genetic analyses enabled us to reveal underlying genetic causes of the patients with epileptic encephalopathy in infancy. Mutations of voltage-gated sodium channel type I alpha subunit gene (SCN1A) are to be causally related with several phenotypes of epilepsy, generalized epilepsy with febrile seizure plus (GEFS+), Dravet syndrome, and other infantile epileptic encephalopathies. In addition to SCN1A, contiguous genes such as SCN2A and SCN3A in 2q24.3 are also reported to have contribution to epileptic seizures. Therefore, gene abnormality involving this region is reasonable to contribute to epilepsy manifestation.

Results: We encountered three patients with 2q24.3 microduplication diagnosed by Array comparative genomic hybridization array (aCGH). They developed partial seizures and epileptic spasms in their early infantile periods and showed remarkable developmental delay, although their seizures disappeared from 11 to 14 months of age. One of three patients had 2q24.3 microduplication which excludes SCN1A. Therefore, characteristics of epilepsy with 2q24.3 microduplication do not necessarily need duplication of SCN1A. This study suggested that 2q24.3 microduplication is one of the causes for early infantile epileptic spasms. Epileptic spasms associated with 2q24.3 microduplications may have better seizure outcome comparing with other etiologies.
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http://dx.doi.org/10.1016/j.braindev.2015.03.001DOI Listing
October 2015

Spinocerebellar ataxias type 27 derived from a disruption of the fibroblast growth factor 14 gene with mimicking phenotype of paroxysmal non-kinesigenic dyskinesia.

Brain Dev 2012 Mar 19;34(3):230-3. Epub 2011 May 19.

Tokyo Women's Medical University Institute for Integrated Medical Sciences, Shinjuku-ward, Tokyo, Japan.

Many types of spinocerebellar ataxias (SCAs) manifest as progressive disorders with cerebellar involvement. SCA type 27 (SCA27) is a rare type of SCA caused by mutations in the fibroblast growth factor 14 gene (FGF14). FGF14 disruption caused by a de novo reciprocal chromosomal translocation between chromosomes 13 and 21 was identified in a patient with the phenotype of paroxysmal non-kinesigenic dyskinesia (PNKD). This indicated genetic heterogeneity of PNKD, since 60% of the patients with PNKD exhibit mutations in another gene responsible for PNKD, the myofibrillogenesis regulator 1 gene (MR-1). We hypothesized that the remaining 40% of patients with PNKD may have FGF14 mutations; therefore, the nucleotide sequences of MR-1 and FGF14 were analyzed in another six patients with PNKD, but no nucleotide alterations were observed in these genes for these patients. Further studies should be conducted on the phenotypic heterogeneity of FGF14 mutations and/or haploinsufficiency in SCA27 and PNKD.
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http://dx.doi.org/10.1016/j.braindev.2011.04.014DOI Listing
March 2012

Cytokine profiles before and after exchange transfusion in a neonate with transient myeloproliferative disorder and hepatic fibrosis.

J Pediatr Hematol Oncol 2010 May;32(4):e164-6

Department of Pediatrics and Neonatology, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan.

Summary: To study the effect of exchange transfusion on cytokine profiles in a patient with transient myeloproliferative disorder and hepatic fibrosis in which cytokines were measured before and after exchange transfusion. A newborn female was diagnosed with Down syndrome phenotypically and on karyotyping. Laboratory data showed a high leukocyte count with blast cells in the peripheral blood and liver dysfunction. Exchange transfusion was performed on day 1. However, respiratory distress and multiorgan failure progressed, and she died after 16 days. Of the cytokines examined, transforming growth factor-beta1 and interleukin-7 were extremely high before exchange transfusion, and decreased after exchange transfusion.
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http://dx.doi.org/10.1097/MPH.0b013e3181d74732DOI Listing
May 2010