Shin Okazaki

Aristaless -related homeobox gene disruption leads to abnormal distribution of GABAergic interneurons in human neocortex: evidence based on a case of X-linked lissencephaly with abnormal genitalia (XLAG)

X-linked lissencephaly with abnormal genitalia (XLAG) is a rare disorder caused by mutations in the aristaless-related homeobox (ARX) gene, located on Xp22.13. Arx-null mice show loss of tangential migration of GABAergic interneurons, presumably being related to caudal ganglionic eminence tangential migration. In the present study, we investigated a subpopulation of GABAergic interneurons in the brain of an infant with XLAG, who had a novel nonsense mutation of the ARX gene, compared with those of age-matched normal controls and Miller–Dieker syndrome. We performed immunocytochemistry for interneuron and migration markers. We found that glutamic acid decarboxylase (GAD)- and calretinin (CR)-containing cells were significantly reduced in the neocortex and located in the white matter and neocortical subventricular zone, while neuropeptide Y- or cholecystokinin-containing cells were normally distributed. Moreover, in the neocortical subventricular region, the GAD- and CR-containing cells expressed the radial migration marker Mash-1 as well as nestin. Our findings suggest that ARX protein controls not only the tangential migration of GABAergic interneurons from the ganglionic eminence, but also may serve to induce radial migration from the neocortical subventricular zone.

Neocortical Layer Formation of Human Developing Brains and Lissencephalies: Consideration of Layer-Specific Marker Expression

To investigate layer-specific molecule expression in human developing neocortices, we performed immunohistochemistry of the layer-specific markers (TBR1, FOXP1, SATB2, OTX1, CUTL1, and CTIP2), using frontal neocortices of the dorsolateral precentral gyri of 16 normal controls, aged 19 gestational weeks to 1 year old, lissencephalies of 3 Miller-Dieker syndrome (MDS) cases, 2 X-linked lissencephaly with abnormal genitalia (XLAG) cases, and 4 Fukuyama-type congenital muscular dystrophy (FCMD) cases. In the fetal period, we observed SATB2+ cells in layers II-IV, CUTL1+ cells in layers II-V, FOXP1+ cells in layer V, OTX1+ cells in layers II or V, and CTIP2+ and TBR1+ cells in layers V and VI. SATB2+ and CUTL1+ cells appeared until 3 months of age, but the other markers disappeared after birth. Neocortices of MDS and XLAG infants revealed SATB2+, CUTL1+, FOXP1+, and TBR1+ cells diffusely located in the upper layers. In fetal FCMD neocortex, neurons labeled with the layer-specific markers located over the glia limitans. The present study provided new knowledge indicating that the expression pattern of these markers in the developing human neocortex was similar to those in mice. Various lissencephalies revealed abnormal layer formation by random migration.

Vitamin B6–responsive epilepsy due to inherited GPI deficiency

Glycosylphosphatidylinositol (GPI) is a glycolipid that anchors many proteins to the cell surface. There are at least 26 genes involved in the biosynthesis of GPI-anchored proteins (GPI-APs).1 Recently, many inherited GPI deficiencies (IGDs) were found using whole-exome sequencing.2–4 The major symptoms of IGDs include mental retardation, epilepsy, coarse facial features, and multiple organ anomalies that vary in severity depending upon the degree of defect and/or position in the pathway of the affected gene. We clarified a mechanism of hyperphosphatasia, an elevated release of tissue-nonspecific alkaline phosphatase (TNAP, GPI-AP), seen in some of the patients with IGDs such as hyperphosphatasia mental retardation syndrome or Mabry syndrome caused by mutation in genes in the later stage of GPI biosynthesis.5

PCDH19-related female-limited epilepsy: Further details regarding early clinical features and therapeutic efficacy

Abnormalities in the protocadherin 19 (PCDH19) gene cause early-onset epilepsy exclusively in females. We aimed to explore the genetic and clinical characteristics of PCDH19-related epilepsy by focusing on its early features and treatment efficacy. PCDH19 was analyzed in 159 Japanese female patients with early-onset epilepsy via direct sequencing and multiplex ligation-dependent probe amplification (MLPA) analysis. We identified 17 patients with PCDH19 abnormalities: point mutations were observed in 14 patients and whole PCDH19 deletions were detected in 3 patients. One affected sister of a proband with a mild phenotype was also analyzed. The frequency of PCDH19 deletion among all probands identified in Japan was 12.5% (3/24, including 7 probands reported previously by us). Clinical features included early onset (mean age at onset, 8.6 months), recurrent clusters of brief seizures (17/18), fever sensitivity (18/18), tonic seizures (13/18, probably including focal tonic seizures), tonic-clonic seizures (8/18), focal seizures often with subsequent generalization (17/18), intellectual disabilities (15/18), and autistic traits (13/18). Three patients exhibited delay in motor milestones before seizure onset. In 16 patients, seizures appeared in clusters from the onset of the disease. Among 6 patients for whom detailed information at onset was available, 2 onset patterns were identified: a biphasic course of short seizure clusters (each within days) in 2 patients and a prolonged course of clusters (from weeks to a month) in 4 patients. In both cases, initial seizures started during fever and transiently disappeared with the decline of fever; however, afebrile clusters recurred. In the former patients, motor development was delayed before onset, and seizures appeared in strong clusters from the onset of the disease. In the latter patients, initial development was normal and initial seizures were mild, but were followed by strong clusters lasting several weeks, even without fever. Treatment using phenytoin, potassium bromide, and clobazam showed high efficacy. Although focal seizures were the main feature in PCDH19-epilepsy, the efficacy of carbamazepine was poor. This study highlighted the significance of PCDH19 deletion, a unique pattern of initial seizure clusters, and the efficacy of antiepileptic drugs. Our data will facilitate early diagnosis and development of a treatment strategy for better clinical management of patients with PCDH19-related epilepsy.

Partial loss of pancreas endocrine and exocrine cells of human ARX-null mutation: consideration of pancreas differentiation.

Aristaless-related homeobox gene (ARX) mutation leads to several neurological disorders including X-linked lissencephaly with abnormal genitalia (XLAG), West syndrome and Partington syndrome, with XLAG being the most severe form. Although some of the brain pathologies of XLAG have already been described, the crucial extra-brain symptoms are severe growth retardation, transient hyperglycemia and intractable diarrhea. Since ARX expresses in the islets of Langerhans during the embryonic stage, these visceral phenotypes may be related to a loss of ARX function, which develops endocrine cells in the pancreas. We investigated the abnormal pancreatic development of XLAG patients with ARX-null mutation. We performed immunohistochemistry of XLAG pancreases, using the antibodies against glucagon, insulin, somatostatin, pancreatic polypeptide, ghrelin, Brn4, Nkx2.2, Mash1, amylase and pancreatic lipase. As the results, the glucagon- and pancreatic polypeptide-producing cells were found to be completely deficient in the islets of Langerhans. We also discovered marked interstitial fibrosis, small exocrine cells with loss of amylase-producing cells and an enlargement of the central lumen of the glandular acini. These pathological findings indicate that ARX contributes not only to endocrine development, but also to exocrine development of the human pancreas, and its deficiency may lead to the severe phenotypes of XLAG patients.

Quinidine therapy for West syndrome with KCNTI mutation: A case report

The KCNT1 gene encodes the sodium-dependent potassium channel, with quinidine being a partial antagonist of the KCNT1 channel. Gain-of-function KCNT1 mutations cause early onset epileptic encephalopathies including migrating partial seizures of infancy (MPSI). At 5months of age, our patient presented with epileptic spasms and hypsarrhythmia by electroencephalogram. Psychomotor retardation was observed from early infancy. The patient was diagnosed with West syndrome. Consequently, various anti-epileptic drugs, adrenocorticotropic hormone therapy (twice), and ketogenic diet therapy were tried. However, the epileptic spasms were intractable. Whole exome sequencing identified a KCNT1 mutation (c.1955G>T; p.G652V). At 2years and 6months, the patient had daily epileptic spasms despite valproate and lamotrigine treatment, and was therefore admitted for quinidine therapy. With quinidine therapy, decreased epileptic spasms and decreased epileptiform paroxysmal activity were observed by interictal EEG. Regarding development, babbling, responsiveness, oral feeding and muscle tone were ameliorated. Only transient diarrhea was observed as an adverse effect. Thus, quinidine therapy should be attempted in patients with West syndrome caused by KCNT1 mutations, as reported for MPSI.

Characteristic Neuroradiologic Features in Hemorrhagic Shock and Encephalopathy Syndrome

Hemorrhagic shock and encephalopathy syndrome is a devastating disease, but the pathogenesis remains unclear. The aim of this study was to examine the usefulness of neuroimaging in establishing a diagnosis and elucidating the pathogenesis. We analyzed the neuroradiologic features of 22 patients who fulfilled the Levin criteria. All patients underwent brain computed tomography (CT), and 14 patients underwent brain magnetic resonance imaging (MRI) including diffusion-weighted imaging in 10 patients. Initial CT showed normal findings in 14 of 18 (78%) patients, but subsequently hypodensities appeared in bilateral watershed zones and progressed to whole brain edema. MRI revealed cytotoxic edema, showing hyperintensities in bilateral watershed zones on diffusion-weighted imaging with a low apparent diffusion coefficient. Serial neuroimaging showed characteristic features of a widespread brain ischemic event mainly in watershed zones in hemorrhagic shock and encephalopathy syndrome.

A case of succinic semialdehyde dehydrogenase deficiency with status epilepticus and rapid regression

BACKGROUND Clinical phenotypic expression of SSADH deficiency is highly heterogeneous, and some infants may develop refractory secondary generalized seizures. PATIENT A 9-month-old boy manifested partial seizures, developing severe status epilepticus, and conventional antiepileptic drugs were ineffective. Use of ketamine contributed to the control of status epilepticus, achieving a reduction in frequency of partial seizures, and improving EEG findings without apparent complications. Diffusion-weighted images showed hyperintensities in the bilateral basal ganglia and fornix, and multiple T2 hyperintensity lesions were detected. (123)I-iomazenil (IMZ) SPECT revealed a decrease in binding of (123)I-iomazenil predominantly in the left temporal region by the 18th day of hospitalization. However, repeated IMZ-SPECT on the 46th day of hospitalization demonstrated almost no accumulation across a broad region, sparing the left temporal region. The patient showed rapid regression, refractory myoclonus, and severe progressive brain atrophy. CONCLUSION IMZ-SPECT findings demonstrated reduced benzodiazepine receptor binding and its dynamic changes in an SSADH-deficient patient. Considering the down regulation of the GABAA receptor, ketamine should be included in pharmacotherapeutic strategies for treatment of refractory status epilepticus in SSADH-deficient patients.

Development and verification of child observation sheet for 5-year-old children.

The aim of the study was to develop a newly devised child observation sheet (COS-5) as a scoring sheet, based on the Childhood Autism Rating Scale (CARS), for use in the developmental evaluation of 5-year-old children, especially focusing on children with autistic features, and to verify its validity. Seventy-six children were studied. The children were recruited among participants of the Japan Childrens Cohort Study, a research program implemented by the Research Institute of Science and Technology for Society (RISTEX) from 2004 to 2009. The developmental evaluation procedure was performed by doctors, clinical psychologists, and public health nurses. The COS-5 was also partly based on the Kyoto Scale of Psychological Development 2001 (Kyoto Scale 2001). Further, the Developmental Disorders Screening Questionnaire for 5-Years-Olds, PDD-Autism Society Japan Rating Scale (PARS), doctor interview questions and neurological examination for 5-year-old children, and the Draw-a-Man Test (DAM) were used as evaluation scales. Eighteen (25.4%) children were rated as Suspected, including Suspected PDD, Suspected ADHD and Suspected MR. The COS-5 was suggested to be valid with favorable reliability (α=0.89) and correlation with other evaluation scales. The COS-5 may be useful, with the following advantages: it can be performed within a shorter time frame; it facilitates the maintenance of observation quality; it facilitates sharing information with other professions; and it is reliable to identify the autistic features of 5-year-old children. In order to verify its wider applications including the screening of infants (18months to 3years old) by adjusting the items of younger age, additional study is needed.

A pediatric patient of hemorrhagic acute transverse myelitis.

An 11-year-old boy presented with progressive leg hypesthesia but no history of trauma. Dysuria and constipation appeared subsequent to gait difficulty. He was admitted 8days after onset. Spinal magnetic resonance imaging (MRI) revealed longitudinal hyperintensity with cord swelling and hypointensity on T2-weighted images, suggesting severe inflammation and microbleeding change, respectively. Gadolinium contrast-enhanced MRI demonstrated mild enhancement in the lesions. Platelet count and coagulation findings were normal, and cerebrospinal fluid analysis showed no pleocytosis. He was diagnosed with idiopathic acute transverse myelitis (ATM), and intravenous methylprednisolone pulse therapy and plasmapheresis were initiated. On day 14, motor dysfunction aggravated suddenly, accompanied by expanding hemorrhagic lesions. Thereafter, administration of intravenous immunoglobulin, repeated intravenous methylprednisolone pulse therapy and prednisolone for one month resulted in complete recovery four months later. Both anti-aquaporin-4 and anti-myelin oligodendrocyte glycoprotein antibodies were negative. We presented the first pediatric case showing hemorrhagic spinal lesions in the clinical course of ATM. This severe complication should be recognized in the management of ATM.