Mutation in VPS33A affects metabolism of glycosaminoglycans: a new type of mucopolysaccharidosis with severe systemic symptoms.

Mucopolysaccharidoses (MPS) are a group of genetic deficiencies of lysosomal enzymes that catabolize glycosaminoglycans (GAG). Here we describe a novel MPS-like disease caused by a specific mutation in the VPS33A gene. We identified several Yakut patients showing typical manifestations of MPS: coarse facial features, skeletal abnormalities, hepatosplenomegaly, respiratory problems, mental retardation, and excess secretion of urinary GAG. However, these patients could not be diagnosed enzymatically as MPS. They showed extremely high levels of plasma heparan sulphate (HS, one of GAG); 60 times the normal reference range and 6 times that of MPS patients. Additionally, most patients developed heart, kidney, and hematopoietic disorders, which are not typical symptoms for conventional MPS, leading to a fatal outcome between 1 and 2-years old. Using whole exome and Sanger sequencing, we identified homozygous c.1492C > T (p.Arg498Trp) mutations in the VPS33A gene of 13 patients. VPS33A is involved in endocytic and autophagic pathways, but the identified mutation did not affect either of these pathways. Lysosomal over-acidification and HS accumulation were detected in patient-derived and VPS33A-depleted cells, suggesting a novel role of this gene in lysosomal functions. We hence propose a new type of MPS that is not caused by an enzymatic deficiency.

Predominant Corticospinal Tract Involvement in a Late Infant with Krabbe Disease.

A case of late-infantile Krabbe disease in a patient who presented with developmental regression and spastic quadriplegia in late infancy is reported. Brain magnetic resonance imaging (MRI) at 11 months of age showed predominant corticospinal tract involvement, which usually appears in adult Krabbe disease. Galactocerebrosidase activity in lymphocytes and skin fibroblasts was very low. Genetic testing revealed compound heterozygous mutations of the galactocerebrosidase (GALC) gene, c.635_646 delinsCTC and c.1901T>C [p.L618S], both of which are known pathogenic mutations. It has been reported that the c.1901T>C [p.L618S] mutation is associated with the late-onset phenotype and, in a past case, a homozygous mutation at this location showed predominant corticospinal tract involvement on MRI. Although further analysis is needed to identify the pathophysiological mechanism, this combination of mutations is likely to be associated with this unusual MRI finding in late-infantile Krabbe disease. Because these types of mutations are common for Japanese patients, it is possible that there are more undiagnosed and late-diagnosed patients of late-infantile Krabbe disease who display limited lesions on MRI. Pediatricians should be aware that patients with late-infantile Krabbe disease can present with predominant corticospinal tract involvement on MRI.

[Relation between psychological development and respiratory management in patients with congenital central hypoventilation syndrome in Japan].

OBJECTIVE: To evaluate the psychological development of patients with congenital central hypoventilation syndrome (CCHS). METHODS: We performed a questionnaire-based survey of 17 patients with CCHS aged over 7 years and assessed their clinical course, respiratory management, and psychological development. RESULTS: CCHS was present at birth in 15 patients, of which eight presented with respiratory failure with a low Apgar score. Twelve patients required mechanical ventilation with intubation, and five received mask ventilation. All patients with intubation underwent tracheostomy between 1 and 12 months of age (median 5.5 months), and most of them had associated conditions such as Hirschsprung disease. Four of 12 patients with intubation were eventually switched to mask ventilation and one to diaphragm pacing and mask ventilation. The patients undergoing mask ventilation had relatively milder disease severity and had fewer complications than did the patients with intubation. The psychological development of patients who received tracheostomy ranged from normal to severe retardation. Retardation was more likely to be severe in patients who received tracheostomy in late infancy. All patients who received mask ventilation experienced borderline to moderate psychological retardation. This effect could be attributed to poor compliance with mask fitting. CONCLUSION: Our findings suggest that the psychological development of CCHS patients was influenced by hypoxia; tracheostomy and strict respiratory management since the neonatal period were needed for neurological protection.

Anti-myelin oligodendrocyte glycoprotein (MOG) antibodies in a Japanese boy with recurrent optic neuritis.

BACKGROUND: Myelin oligodendrocyte glycoprotein (MOG) localizes on the outermost surface of the myelin sheath and oligodendrocytes in the central nervous system (CNS). Autoantibodies against MOG are reportedly found in patients with spectrum of inflammatory demyelinating diseases of the CNS, including acute disseminated encephalomyelitis, multiple sclerosis, and neuromyelitis optica. In addition, recent studies have emphasized an association between anti-MOG antibodies and optic neuritis. PATIENT: We present the first case report of a 7-year-old Japanese boy who was positive for anti-MOG antibodies. He experienced four episodes of unilateral optic neuritis and one seizure event. Magnetic resonance imaging revealed T2-hyperintense lesions in the subcortical white matter and midbrain. Although he fulfilled the diagnostic criteria for multiple sclerosis, recombinant interferon beta did not prevent recurrence. Established cell-based immunoassays revealed that he was positive for anti-MOG antibodies and negative for anti-aquaporin 4 antibodies. CONCLUSIONS: Our case report supports the relationship between anti-MOG antibodies and recurrent optic neuritis. Additional studies are needed to establish the clinical significance of anti-MOG antibodies for diagnosis, treatment, and prognosis.

Pontine malformation, undecussated pyramidal tracts, and regional polymicrogyria: a new syndrome.

BACKGROUND: Horizontal gaze palsy and progressive scoliosis is caused by mutations in the ROBO3 gene, which plays a role in axonal guidance during brain development. Horizontal gaze palsy and progressive scoliosis is characterized by the congenital absence of conjugate lateral eye movements with preserved vertical gaze and progressive scoliosis as well as dysgenesis of brainstem structures and ipsilateral projection of the pyramidal tract. PATIENT: A 4-year, 11-month, girl presented with psychomotor retardation and autistic traits. Magnetic resonance imaging revealed hypoplasia and malformation of the ventral portion of the pons and medulla oblongata. Diffusion tensor imaging revealed the absence of decussation of the bilateral pyramidal tracts. These findings were similar to the typical findings for horizontal gaze palsy and progressive scoliosis. However, restriction of horizontal eye movement was minimal, and bilateral polymicrogyria were also noted in the occipitotemporal cortex in the present patient. These findings have not been previously reported in patients with horizontal gaze palsy and progressive scoliosis. No mutations in the ROBO3, SLIT1, SLIT2, NTN1, SEMA3 A, or SEMA3 F genes were identified. CONCLUSION: This child may have a disorder caused by an unidentified factor, other than a mutation in the genes analyzed, involved in corticogenesis, axonal guidance, and brainstem morphogenesis.

Utility of real-time three-dimensional echocardiography for Duchenne muscular dystrophy with echocardiographic limitations.

Duchenne muscular dystrophy (DMD) is strongly associated with a unique form of dilated cardiomyopathy. Cardiac complications are the leading cause of death in DMD; thus, longitudinal assessments and early intervention for cardiac dysfunction are necessary to improve prognosis. Two-dimensional echocardiography, which is routinely used for cardiac assessment, has some limitations for quantitative analyses in DMD patients with thoracic deformities and regional wall motion abnormalities in the left ventricle. Recently, real-time three-dimensional echocardiography has emerged as a feasible tool for cardiac assessment in various cardiac diseases. The aim of this study was to examine the utility of this technology in DMD. We evaluated left ventricular ejection fraction (LVEF), a major parameter of left ventricular function, in 17 male DMD patients. LVEF values measured by real-time three-dimensional echocardiography were compared with those determined by two established nuclear cardiology methods: "the first-pass method of radionuclide angiocardiography" and "quantitative electrocardiogram-gated single-photon emission computed tomography". A good correlation was observed for LVEF values, particularly between real-time three-dimensional echocardiography and "the first-pass method of radionuclide angiocardiography" (r=0.90, p<0.05). Thus, real-time three-dimensional echocardiography can provide an accurate measurement of LVEF in DMD patients with echocardiographic limitations.

[Clinical features of congenital myasthenic syndrome in Japan].

OBJECTIVE: We examined the clinical and neurophysiological features of Japanese patients with congenital myasthenic syndrome (CMS). METHOD: Subjects were five patients who were diagnosed with CMS on the basis of clinical course, repetitive nerve stimulation (RNS), and genetic analysis. RESULTS: Four patients manifested motor retardation within one year of birth, while one manifested motor intolerance at three years of age. The most characteristic symptom observed in all the patients was fluctuating muscle weakness, which varied on a daily basis or continued for several days after the late infancy period. Only one patient manifested daily fluctuation of muscle weakness. RNS of the accessory nerve evoked a decrementing response in three patients who were examined;however, RNS of the median, ulnar, and tibial nerves (one patient each) did not evoke such responses. After the edrophonium chloride test, no improvement was seen even if the patients manifested ptosis. For judgment of this test, improvement in decrementing rate observed while performing RNS was useful. All five patients who were administered medication based on the results of genetic analysis demonstrated an improvement in their symptoms. CONCLUSION: We suggest that CMS can be diagnosed based on careful examination and electrophysiological results. CMS is a treatable disorder, and therefore, correct diagnosis is important.

High gamma activity of 60-70 Hz in the area surrounding a cortical tuber in an infant with tuberous sclerosis.

PURPOSE: To detect the epileptogenic region causing epileptic spasms in an infant with tuberous sclerosis (TS). METHODS: We applied a multiple band frequency analysis to video electroencephalographic (EEG) recordings of the infant's scalp. We also performed computed tomography (CT), magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT), and magnetoencephalography (MEG) of the brain in order to ascertain the epileptic focus. RESULTS: During the periodic spasms, we identified fast ictal activity with frequencies of 60-70 Hz in the right centroparietal region. This region was part of the area surrounding the largest cortical tuber that was identified on CT and MRI and was located in the right frontal lobe. An area of increased blood perfusion that was observed with SPECT and dipole sources that were determined with interictal MEG were also located in this area. In addition, ictal frequency oscillations (FOs) with high gamma activity were identified over the cortex surrounding the largest tuber. After a lesionectomy of this tuber, the periodic spasms disappeared, and no FOs were detected over this area. CONCLUSIONS: Scalp EEG, which identified the ictal onset zone by detecting fast activity that was suggestive of FOs, was useful for detecting the epileptogenic region in an infant with TS.

Effects of acetazolamide on epileptic apnea in migrating partial seizures in infancy.

We report two cases of migrating partial seizures in infancy complicated with intractable epileptic apnea with severe desaturation. Ictal electroencephalography revealed migrating foci of epileptiform discharges, which spread to bilateral temporal areas resulting in the onset of apnea. Magnetoencephalography detected dipole sources at bilateral perisylvian areas. Single photon emission tomography revealed a significant ictal change in perfusion at bilateral anterior temporal lobes in one patient. Addition of acetazolamide to the regimen resulted in complete disappearance of epileptic seizures.