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Background and Objectives: Genetic white matter disorders (GWMD) are of heterogeneous origin, with >100 causal genes identified to date. Classic targeted approaches achieve a molecular diagnosis in only half of all patients. We aimed to determine the clinical utility of singleton whole-exome sequencing and whole-genome sequencing (sWES-WGS) interpreted with a phenotype- and interactome-driven prioritization algorithm to diagnose GWMD while identifying novel phenotypes and candidate genes., Methods: A case series of patients of all ages with undiagnosed GWMD despite extensive standard-of-care paraclinical studies were recruited between April 2017 and December 2019 in a collaborative study at the Bellvitge Biomedical Research Institute (IDIBELL) and neurology units of tertiary Spanish hospitals. We ran sWES and WGS and applied our interactome-prioritization algorithm based on the network expansion of a seed group of GWMD-related genes derived from the Human Phenotype Ontology terms of each patient., Results: We evaluated 126 patients (101 children and 25 adults) with ages ranging from 1 month to 74 years. We obtained a first molecular diagnosis by singleton WES in 59% of cases, which increased to 68% after annual reanalysis, and reached 72% after WGS was performed in 16 of the remaining negative cases. We identified variants in 57 different genes among 91 diagnosed cases, with the most frequent being RNASEH2B , EIF2B5 , POLR3A , and PLP1 , and a dual diagnosis underlying complex phenotypes in 6 families, underscoring the importance of genomic analysis to solve these cases. We discovered 9 candidate genes causing novel diseases and propose additional putative novel candidate genes for yet-to-be discovered GWMD., Discussion: Our strategy enables a high diagnostic yield and is a good alternative to trio WES/WGS for GWMD. It shortens the time to diagnosis compared to the classical targeted approach, thus optimizing appropriate management. Furthermore, the interactome-driven prioritization pipeline enables the discovery of novel disease-causing genes and phenotypes, and predicts novel putative candidate genes, shedding light on etiopathogenic mechanisms that are pivotal for myelin generation and maintenance., (Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)

The neurological phenotype of 3-hydroxyisobutyryl-CoA hydrolase (HIBCH) and short-chain enoyl-CoA hydratase (SCEH) defects is expanding and natural history studies are necessary to improve clinical management. From 42 patients with Leigh syndrome studied by massive parallel sequencing, we identified five patients with SCEH and HIBCH deficiency. Fourteen additional patients were recruited through collaborations with other centres. In total, we analysed the neurological features and mutation spectrum in 19 new SCEH/HIBCH patients. For natural history studies and phenotype to genotype associations we also included 70 previously reported patients. The 19 newly identified cases presented with Leigh syndrome (SCEH, n = 11; HIBCH, n = 6) and paroxysmal dystonia (SCEH, n = 2). Basal ganglia lesions (18 patients) were associated with small cysts in the putamen/pallidum in half of the cases, a characteristic hallmark for diagnosis. Eighteen pathogenic variants were identified, 11 were novel. Among all 89 cases, we observed a longer survival in HIBCH compared to SCEH patients, and in HIBCH patients carrying homozygous mutations on the protein surface compared to those with variants inside/near the catalytic region. The SCEH p.(Ala173Val) change was associated with a milder form of paroxysmal dystonia triggered by increased energy demands. In a child harbouring SCEH p.(Ala173Val) and the novel p.(Leu123Phe) change, an 83.6% reduction of the protein was observed in fibroblasts. The SCEH and HIBCH defects in the catabolic valine pathway were a frequent cause of Leigh syndrome in our cohort. We identified phenotype and genotype associations that may help predict outcome and improve clinical management., (© 2020 SSIEM.)

GMPPB mutations cause congenital myasthenic syndromes (CMS) overlapping with muscular dystrophy. Treatment with pyridostigmine has been reported to be effective in those patients. Nevertheless, results of functional motor assessments to determine its precise impact on the short and long term were not available. We describe the response to treatment with pyridostigmine in three siblings with GMPPB-related CMS using functional motor scales performed regularly over a period of 40 months. The beneficial effect of the treatment was outstanding within the first hours, with all the scales showing a dramatic increase in only two days. This remarkable improvement remained steady during 12 months but a moderate decrease was subsequently detected in two of the three patients. Despite this decline in the scores of the scales at the end of follow up, the functional motor status of the patients was still significantly better than it was before starting treatment. The introduction of pyridostigmine at an early age of the disease in one of the patients, before the onset of scoliosis, may have had a protective effect on it., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Sphingolipid imbalance is the culprit in a variety of neurological diseases, some affecting the myelin sheath. We have used whole-exome sequencing in patients with undetermined leukoencephalopathies to uncover the endoplasmic reticulum lipid desaturase DEGS1 as the causative gene in 19 patients from 13 unrelated families. Shared features among the cases include severe motor arrest, early nystagmus, dystonia, spasticity, and profound failure to thrive. MRI showed hypomyelination, thinning of the corpus callosum, and progressive thalamic and cerebellar atrophy, suggesting a critical role of DEGS1 in myelin development and maintenance. This enzyme converts dihydroceramide (DhCer) into ceramide (Cer) in the final step of the de novo biosynthesis pathway. We detected a marked increase of the substrate DhCer and DhCer/Cer ratios in patients' fibroblasts and muscle. Further, we used a knockdown approach for disease modeling in Danio rerio, followed by a preclinical test with the first-line treatment for multiple sclerosis, fingolimod (FTY720, Gilenya). The enzymatic inhibition of Cer synthase by fingolimod, 1 step prior to DEGS1 in the pathway, reduced the critical DhCer/Cer imbalance and the severe locomotor disability, increasing the number of myelinating oligodendrocytes in a zebrafish model. These proof-of-concept results pave the way to clinical translation.

Mitochondrial DNA depletion syndrome (MDS) is a clinically heterogeneous group of mitochondrial disorders characterised by a quantitative reduction of the mitochondrial DNA copy number. Three main clinical forms of MDS: myopathic, encephalomyopathic and hepatocerebral have been defined, although patients may present with other MDS associated clinical symptoms and signs that cover a wide spectrum of onset age and disease. We studied 52 paediatric individuals suspected to have MDS. These patients have been divided into three different groups, and the appropriate MDS genes have been screened according to their clinical and biochemical phenotypes. Mutational study of DGUOK, MPV17, SUCLA2, SUCLG1 and POLG allowed us to identify 3 novel mutations (c.1048G>A and c.1049G>T in SUCLA2 and c.531+4A>T in SUCLG1) and 7 already known mutations in 10 patients (8 families). Seventeen patients presented with mtDNA depletion in liver or muscle, but the cause of mtDNA depletion still remains unknown in 8 of them. When possible, we quantified mtDNA/nDNA and CS activity in the same tissue sample, providing an additional tool for the study of MDS. The ratio (mtDNA/nDNA)/CS has shed some light in the discrepant results between the mtDNA copy number and the enzymatic respiratory chain activities of some cases., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The transcription factor EGR2 is expressed in Schwann cells, where it controls peripheral nerve myelination. Mutations of EGR2 have been found in patients with congenital hypomyelinating neuropathy or Charcot-Marie-Tooth disease type 1D. In a patient with congenital amyelinating neuropathy, we observed pathological abnormalities recapitulating the peripheral nervous system phenotype of homozygous Egr2-null mice. This patient, born from consanguineous parents, showed no EGR2 immunoreactivity in Schwann cells and harbored a homozygous 10.7-kilobase-long deletion encompassing a myelin-specific enhancer of EGR2. This regulatory mutation is the first genetic abnormality associated with congenital amyelinating neuropathy in humans., (Copyright © 2012 American Neurological Association.)

Background: To estimate the annual incidence rate of epilepsy, as well as the relative distribution of the different epilepsies and epileptic syndromes in children., Material and Methods: All incident cases of children living in Navarre below 15 years of age with a newly diagnosed epilepsy (years 2003 through 2005) have been registered in a prospective study. Epidemiological and clinical data and complementary studies were collected. ILAE guidelines for epidemiological studies were applied., Results: One hundred and forty two patients were diagnosed with child epilepsy (18 infants, 47 early children, 39 school children and 38 adolescents). The annual incidence rate was 62.1 cases per 100.000 (95% CI: 61.6-62.6), with a highest incidence rate during the first year of life (103.9 per 100.000). Fifty seven percent of the patients presented focal epilepsies, 41.5% generalized and 1.4% undetermined. In infants, West syndrome (44.4%), epilepsies associated to specific syndromes (27.7%) and focal symptomatic (11.1%) were the most prevalent epileptic syndromes. In early childhood, the main syndromes were focal symptomatic (21.3%) or cryptogenic epilepsies (25.5%). In schoolchildren, focal idiopathic (25.6%) and cryptogenic epilepsies (20.5%). And, in adolescents, focal cryptogenic (21.1%) and idiopathic epilepsies (18.4%)., Conclusions: The annual incidence rate of child epilepsy in Navarre shows a similar rate as described for other western countries, with the highest incidence rate during the first year of life, diminishing gradually until adolescence. Published data concerning relative frequency of epilepsy and epileptic syndromes are quite discordant. The difficulties in establishing a syndromic diagnosis require the application of uniform criteria in order to obtain valid and comparable epidemiological information.

The evaluation of psychomotor development is one of the basic activities of everyday paediatric practice, since it helps us not only to determine if the child shows some alteration but also to confirm that the child is healthy. It is thus essential to be able to carry out a suitable evaluation, given that an alteration in this might be the only expression of a disorder of the nervous system. Early detection of any dysfunction contributes to a possible early treatment and to minimising the appearance of sequels. A description is given of the normal development of the child up until 2 years, and an analysis is made of the areas of development, variants of normality and the warning signals classified chronologically. From amongst the different tests and appraisal scales, we give the most detailed exposition of the Hizea-Llevant test, since it is applicable to children between 0 and 5 years old, and because it makes it possible to check development in the cognitive, social and motor areas in a simple and rapid way.

Introduction: Cockayne syndrome (CS) is a rare autosomal recessive disease which is characterized by physical and mental retardation, progressive neurological disfunction, photosensitivity and other cutaneous features. Usually they present ophthalmologic abnormalities as well as other heterogenous clinical, radiological and pathologic features as leucodistrophy and calcifications in central nervous system and segmental demyelination in peripheral nervous system., Clinical Cases: Two brothers, sons of healthy unrelated parents, are presented. The first patient was referred at 8 months of age because of psychomotor retardation and the second one at 5 months old because of a cataract. At the age of 2 years both presented a complex clinical picture with photosensitivity, growth and mental retardation, peripheral neuropathy, neurosensorial deafness, and cerebral atrophy and calcifications in neuroimaging diagnosis tests. In the following years the older brother presented signs of renal failure, cataracts and retinopathy, and died at 9 years old because of a respiratory infection. The neuropathologic study showed a discrete neuronal loss and diffuse demyelination with calcium deposits in cerebral white matter and basal ganglia. Today the second patient is 8 years old and shows a clinical course similar to that of his brother., Conclusions: Clinical, radiologic and pathologic features in our patients support the diagnosis of CS type II.

Lysinuric protein intolerance (LPI; MIM 222700) is an autosomal recessive disorder characterized by defective transport of the cationic amino acids lysine, arginine and ornithine at the basolateral membrane of the polar epithelial cells in the intestine and renal tubules, and by hyperammonemia after high-protein meals. LPI is caused by mutations in the SLC7A7 (solute carrier family 7, member 7) gene encoding y(+)LAT-1 (y(+)L amino acid transporter-1), which co-induces together with 4F2 heavy chain (4F2hc) system y(+)L in Xenopus oocytes. All Finnish LPI patients share the same founder mutation 1181-2A-->T (LPI(Fin)) not found in LPI patients elsewhere. Mutation screening of 20 non-Finnish LPI patients revealed 10 novel mutations: four deletions, two missense mutations, two nonsense mutations, a splice site mutation and a tandem duplication. Five LPI mutations (L334R, G54V, 1291delCTTT, 1548delC and LPI(Fin)) were studied functionally. All mutant proteins failed to co-induce amino acid transport activity when expressed with 4F2hc in Xenopus oocytes. Immunostaining experiments revealed that frameshift mutants 1291delCTTT, 1548delC and LPI(Fin)remained intracellular on expression with 4F2hc. In contrast, the missense mutants L334R and G54V reached the oocyte plasma membrane when co-expressed with 4F2hc, demonstrating that they are transport-inactivating mutations. This finding, together with the strong degree of conservation among all members of this family of amino acid transporters, indicates that residues L334 and G54 play a crucial role in the function of the y(+)LAT-1 transporter.

Introduction and Clinical Cases: We present two patients who at the ages of 5 and 17 months respectively presented with convulsive crises with motor signs, of partial onset and secondary generalization, which eventually became normal. Both patients had a family history of first degree relatives with similar illnesses and are at present-five years later-well and with normal development, school achievement and neurological examination findings. The clinical characteristics, normal biochemical and neuroimaging investigations and EEG characteristics suggest the diagnosis of benign partial epilepsy of early infancy. This syndrome is characterized by its appearance during the first year of life, having no known etiological factors, with partial crises occurring several times a day and with a course leading to remission. Its frequency may be greater than is thought. There is a pattern of dominant autosomal inheritance, with a gene recently found on chromosome 19., Conclusion: We consider that this syndrome should be included in the International Classification of Epilepsy and Epileptic Syndromes as benign familial idiopathic partial epilepsy.

Introduction: Peripheral neuropathy with agenesis of the corpus callosum (or Andermann's syndrome) is a hereditary autosomal recessive disorder rarely found outside certain regions of Quebec Province (Canada). It is associated with mental retardation and various dysmorphic changes. Deterioration is usually progressive with loss of motor skills, development of scoliosis during adolescence, tendency to behaviour disorders and death during the third decade (approximately)., Clinical Case: We present a 13 year old girl diagnosed as having the spastic tetraparesic type of PCI, who was sent to us so that we could reconsider the diagnosis in view of the atypical course of the illness. The patient had an unusual phenotype with dysmorphic changes (mainly facial), axial hypotonia with flexion-retraction of the hands, generalized arreflexia, neurogenic bladder, skin changes with ulcers on the legs and mental retardation. Neurophysiological studies showed a predominantly motor polyneuropathy. There were signs of axonal neuropathy on both sural nerve and skeletal muscle biopsies. The clinical features, phenotype, microcephaly with agenesis of the corpus callosum and a posterior fossa cyst, associated with spinal atrophy indicated the diagnosis of Andermann's syndrome., Conclusions: This case is of interest in view of the exceptional rarity of Andermann's syndrome in our population.

Tissue plasminogen activator (t-PA) activity was studied in three different experimental models of male Wistar rats; hepatic lesion without portal hypertension, portal hypertension without hepatic lesion and portal hypertension plus function liver suppression by ligation of both portal vein and hepatic artery. t-PA activity was higher in animals with portal hypertension alone than in animals with only hepatic lesion (146%). Maximal values were present in animals with functional liver suppression (1.774% vs. controls, 248% vs. hepatic lesion and 169% vs. portal hypertension only). These results suggest that both reduced hepatic t-PA clearance and portal hypertension could be involved in the increased t-PA activity normally appearing in chronic liver disease.

The clinical manifestation of McArdle disease rarely occur in children. A brother and a sister aged 12 and 7 years respectively are presented. Both are sons of a consanguinous marriage. The clinical manifestations of the girl began when she was seven. The dominant clinical feature was her difficulty in performing physical exercises. At this time the brother was asymptomatic. There were no abnormalities on physical examination. The level of the serum CK was fluctuating at a level above normal in both patients. There was not lactic acidosis after exercise test. The level of lactic acid didn't rise after McArdle test with ischemia of the forearm in both, however the plasmatic ammonium rose six or seven times above the basal level. The electromyography showed in the girl electric silence without pain and stiffness after ischemia of the forearm. The muscle biopsy performed by a Bergström needle showed in both a subsarcolemmal glycogen accumulations. The histochemical reaction for phosphorylase was absent, the biochemical investigations confirmed the absence of this enzyme. A hyperproteique diet did not release the clinical manifestations of the patients.

A review of 20 cases of giant axonal neuropathy (4 of them familial) described in the literature, and two new cases in brothers whose parents had no consanguinity is reported. A recessive autosomic pattern of inheritance is suggested. Curly hair, a typical phenotypic feature, was not initially present in our cases. This feature developed, however, later in the older brother. Clinical manifestations include an early predominantly motor polyneuropathy, subsequently involving the central nervous system. Clinical course is progressive and gait becomes impaired by the age of 10 to 13 years. Electrophysiologic studies show an axonal polyneuropathy with decreased evoked potential amplitude in motor and sensitive conduction speed. Diagnosis is achieved through a sural nerve biopsy showing an axonal thickening. Electron microscopy shows this to be related to a neurofibrillar accumulation.

Six newborn infants with myocardial infarction are presented. All of them had a history of perinatal hypoxemia and their natal weights were below 2,500 g. All infants developed cardiogenic "shock" during and required assisted ventilation. Autopsy confirmed the diagnosis in five of the six infants. Other autopsy findings were intracranial bleeding (three cases) and pulmonary atelectasis (two cases). Authors review pathophysiology of this clinical picture and point out its possible influence in the origin of neonatal shock.