Genetic Heterogeneity Underlying Phenotypes with Early-Onset Cerebellar Atrophy.

Cerebellar atrophy (CA) is a frequent neuroimaging finding in paediatric neurology, usually associated with cerebellar ataxia. The list of genes involved in hereditary forms of CA is continuously growing and reveals its genetic complexity. We investigated ten cases with early-onset cerebellar involvement with and without ataxia by exome sequencing or by a targeted panel with 363 genes involved in ataxia or spastic paraplegia. Novel variants were investigated by in silico or experimental approaches. Seven probands carry causative variants in well-known genes associated with CA or cerebellar hypoplasia: SETX, CACNA1G, CACNA1A, CLN6, CPLANE1, and TBCD. The remaining three cases deserve special attention; they harbour variants in MAST1, PI4KA and CLK2 genes. MAST1 is responsible for an ultrarare condition characterised by global developmental delay and cognitive decline; our index case added ataxia to the list of concomitant associated symptoms. PIK4A is mainly related to hypomyelinating leukodystrophy; our proband presented with pure spastic paraplegia and normal intellectual capacity. Finally, in a patient who suffers from mild ataxia with oculomotor apraxia, the de novo novel CLK2 c.1120T>C variant was found. The protein expression of the mutated protein was reduced, which may indicate instability that would affect its kinase activity.

Variant in CACNA1G as a Possible Genetic Modifier of Neonatal Epilepsy in an Infant with a De Novo SCN2A Mutation.

Mutations in SCN2A genes have been described in patients with epilepsy, finding a large phenotypic variability, from benign familial epilepsy to epileptic encephalopathy. To explain this variability, it was proposed the existence of dominant modifier alleles at one or more loci that contribute to determine the severity of the epilepsy phenotype. One example of modifier factor may be the CACNA1G gene, as proved in animal models. We present a 6-day-old male newborn with recurrent seizures in which a mutation in the SCN2A gene is observed, in addition to a variant in CACNA1G gene. Our patient suffered in the first days of life myoclonic seizures, with pathologic intercritical electroencephalogram pattern, requiring multiple drugs to achieve adequate control of them. During the next weeks, the patient progressively improved until complete remission at the second month of life, being possible to withdraw the antiepileptic treatment. We propose that the variant in CACNA1G gene could have acted as a modifier of the epilepsy syndrome produced by the mutation in SCN2A gene in our patient.

N-Type Ca Channel in Epileptic Syndromes and Epilepsy: A Systematic Review of Its Genetic Variants.

N-type voltage-gated calcium channel controls the release of neurotransmitters from neurons. The association of other voltage-gated calcium channels with epilepsy is well-known. The association of N-type voltage-gated calcium channels and pain has also been established. However, the relationship between this type of calcium channel and epilepsy has not been specifically reviewed. Therefore, the present review systematically summarizes existing publications regarding the genetic associations between N-type voltage-dependent calcium channel and epilepsy.

Extending the Phenotype Related to SCN1A Gene: Arthrogryposis, Movement Disorders, and Malformations of Cortical Development.

BACKGROUND: Expand the knowledge about the clinical phenotypes associated with pathogenic or likely pathogenic variants in the SCN1A gene. METHODS: The study was carried out in 15 patients with SCN1A variants. The complete phenotype of the patients was evaluated. A systematic search was carried out in the scientific literature for those unexpected symptoms. RESULTS: Ten patients showed a missense variant, whereas the remaining showed different loss-of-function variants. Twelve (80%) had Dravet syndrome. Two (13.3%) had Epilepsy with febrile seizures plus. Three (20%) presented an atypical phenotype. One of them was developmental and epileptic encephalopathy with arthrogryposis, the other Dravet syndrome and movement disorder, and lastly one patient had Dravet syndrome and malformations of the cortical development. CONCLUSION: The exhaustive assessment of patients with pathogenic alterations detected in massive sequencing can help us to expand the phenotype, understand the etiopathogenesis associated with each genetic abnormality, and thus improve the prognosis and management of future patients.

Extending the clinical phenotype of SPTAN1: From DEE5 to migraine, epilepsy, and subependymal heterotopias without intellectual disability.

Mutations in SPTAN1 gene, encoding the nonerythrocyte αII-spectrin, are responsible for a severe developmental and epileptic encephalopathy (DEE5) and a wide spectrum of neurodevelopmental disorders, as epilepsy with or without intellectual disability (ID) or ID with cerebellar syndrome. A certain genotype-phenotype correlation has been proposed according to the type and location of the mutation. Herein, we report three novel cases with de novo SPTAN1 mutations, one of them associated to a mild phenotype not previously described. They range from (1) severe developmental encephalopathy with ataxia and a mild cerebellar atrophy, without epilepsy; (2) moderate intellectual disability, severe language delay, ataxia and tremor; (3) normal intelligence, chronic migraine, and generalized tonic-clonic seizures. Remarkably, all these patients showed brain MRI abnormalities, being of special interest the subependymal heterotopias detected in the latter patient. Thus we extend the SPTAN1-related phenotypic spectrum, both in its radiological and clinical involvement. Furthermore, after systematic analysis of all the patients so far reported, we noted an excess of male versus female patients (20:9, p = 0.04), more pronounced among the milder phenotypes. Consequently, some protection factor might be suspected among female carriers, which if confirmed should be considered when establishing the pathogenicity of milder genetic variants in this gene.

Mitochondrial developmental encephalopathy with bilateral optic neuropathy related to homozygous variants in IMMT gene.

IMMT gene codes for mitofilin, a mitochondrial inner membrane protein that regulates the morphology of mitochondrial cristae. The phenotype associated with mutations in this gene has not been yet established, but functional studies carried out show that its loss causes a mitochondrial alteration, both in the morphology of the mitochondrial crests and in their function. We present two cousins from an extended highly consanguineous family with developmental encephalopathy, hypotonia, nystagmus due to optic neuropathy. The likely pathogenic homozygous c.895A>G (p.Lys299Glu) variant in the IMMT gene co-segregates with the disease and associates altered mitochondrial cristae observed by electron microscopy.

Case Report: Novel Homozygous Likely Pathogenic SCN1A Variant With Autosomal Recessive Inheritance and Review of the Literature.

Dominant pathogenic variations in the SCN1A gene are associated with several neuro developmental disorders with or without epilepsy, including Dravet syndrome (DS). Conversely, there are few published cases with homozygous or compound heterozygous variations in the SCN1A gene. Here, we describe two siblings from a consanguineous pedigree with epilepsy phenotype compatible with genetic epilepsy with febrile seizures plus (GEFS+) associated with the homozygous likely pathogenic variant (NM_001165963.1): c.4513A > C (p.Lys1505Gln). Clinical and genetic data were compared to those of other 10 previously published patients with epilepsy and variants in compound heterozygosity or homozygosity in the SCN1A gene. Most patients (11/12) had missense variants. Patients in whom the variants were located at the cytoplasmic or the extracellular domains frequently presented a less severe phenotype than those in whom they are located at the pore-forming domains. Five of the patients (41.7%) meet clinical criteria for Dravet syndrome (DS), one of them associated acute encephalopathy. Other five patients (41.7%) had a phenotype of epilepsy with febrile seizures plus familial origin, while the two remaining (17%) presented focal epileptic seizures. SCN1A-related epilepsies present in most cases an autosomal dominant inheritance; however, there is growing evidence that some genetic variants only manifest clinical symptoms when they are present in both alleles, following an autosomal recessive inheritance.

Venous sinus thrombosis in pediatrics. Case series of a tertiary hospital. / Trombosis de senos venosos en pediatría. Serie de casos de un hospital terciario.

INTRODUCTION: Venous sinus thrombosis (VST) is a rare entity in pediatrics, probably under-diagnosed and poten tially serious, described as a cause of stroke in childhood. OBJECTIVE: To describe the clinical presenta tion, risk factors, treatment, and evolution of pediatric patients with VST. PATIENTS AND METHOD: Re trospective study of patients admitted to a referral hospital, diagnosed with VST, aged between one month and seventeen years, from January 2011 to December 2019. The following data were re viewed: age at diagnosis, sex, signs and symptoms of presentation, predisposing mechanisms, study of thrombophilias, treatment and duration of treatment, follow-up protocol, long-term sequelae, and mortality. Due to their differences in clinical presentation, the sample was divided into two age groups: young children between 1 month and 5 years and older children and adolescents between 6 and 17 years. RESULTS: 17 patients were diagnosed with VST, 45% were women, with a median age of 4.5 years. The most frequent symptoms in older children (6-17 years old) were headache (80%) and diplopia (60%). In children under 5 years old, the most frequent clinical presentation was cerebellar ataxia (42%), asymptomatic (34%), and headache (25%). In 23.5% of the total, VST was a casual fin ding in neuroimaging. 13 patients presented relevant histories such as complicated otitis media with mastoiditis (53%), severe traumatic head injury (6%), and resection of a space-occupying lesion of the brain (6%). 23% of the cases were idiopathic and in 23% there were prothrombotic factors. The treatment of choice in all patients was low-molecular-weight heparin. During the short-term follow- up, 11.8% presented self-limited neurological symptoms. One patient presented long-term paresis of the sixth paired cranial nerve. There were no deaths or recurrences of the episode in our series. CONCLUSIONS: VST is a rare entity and it usually appears with signs and symptoms of intracranial hy pertension. It is a potentially serious condition and early diagnosis and treatment can help minimize long-term sequelae.

Genetics of Paroxysmal Dyskinesia: Novel Variants Corroborate the Role of KCNA1 in Paroxysmal Dyskinesia and Highlight the Diverse Phenotypic Spectrum of KCNA1- and SLC2A1-Related Disorders.

Paroxysmal dyskinesias (PxD) are rare movement disorders with characteristic episodes of involuntary mixed hyperkinetic movements. Scientific efforts and technical advances in molecular genetics have led to the discovery of a variety of genes associated with PxD; however, clinical and genetic information of rarely affected genes or infrequent variants is often limited. In our case series, we present two individuals with PxD including one with classical paroxysmal kinesigenic dyskinesia, who carry new likely pathogenic de novo variants in KCNA1 (p.Gly396Val and p.Gly396Arg). The gene has only recently been discovered to be causative for familial paroxysmal kinesigenic dyskinesia. We also provide genetic evidence for pathogenicity of two newly identified disease-causing variants in SLC2A1 (p.Met96Thr and p.Leu231Pro) leading to paroxysmal exercise-induced dyskinesia. Since clinical information of carriers of variants in known disease-causing genes is often scarce, we encourage to share clinical data of individuals with rare or novel (likely) pathogenic variants to improve disease understanding.

Hidden etiology of cerebral palsy: genetic and clinical heterogeneity and efficient diagnosis by next-generation sequencing.

Cerebral palsy (CP) is a heterogeneous neurodevelopmental disorder that causes movement and postural disabilities. Recent research studies focused on genetic diagnosis in patients with CP of unknown etiology. The present study was carried out in 20 families with one family member affected with idiopathic CP. Chromosomal microarray and exome sequencing techniques were performed in all patients. Chromosomal microarray analysis did not show any pathological or probable pathological structural variant. However, the next-generation sequencing study showed a high diagnostic yield. We report 11/20 patients (55%) with different pathogenic or potentially pathogenic variants detected by exome sequencing analysis: five patients with mutations in genes related to hereditary spastic paraplegia, two with mutations in genes related to Aicardi-Goutières syndrome, three with mutations in genes related to developmental/epileptic encephalopathies, and one with a mutation in the PGK1 gene. The accurate and precise patients' selection, the use of a high-throughput genetic platform, the selection of adequate target genes, and the application of rigorous criteria for the clinical interpretation are the most important elements for a good diagnostic performance. Based on our findings, next-generation sequencing should be considered in patients with cryptogenic CP as the first line of genetic workup. IMPACT: Sequencing techniques in CP of uncertain etiology provides a diagnostic yield of 55%. The appropriate selection of cases optimizes the diagnostic yield. NGS facilitate better understanding of new phenotypes of certain genetic diseases.

Secuelas neurológicas en pacientes con infección congénita por citomegalovirus / Neurological sequelae in patients with congenital citomegalovirus

INTRODUCCIÓN: La infección por citomegalovirus es la infección congénita más frecuente en los países desarrollados y una de las principales causas de retraso psicomotor y sordera neurosensorial de origen infeccioso. El presente estudio tiene como objetivos describir las características clínico-analíticas y de neuroimagen de los pacientes con secuelas neurológicas secundarias a la infección congénita por citomegalovirus y compararlas con el grupo de pacientes con infección congénita por citomegalovirus que no presentaron clínica neurológica durante su seguimiento. Material y MÉTODOS: Estudio de cohortes retrospectivo, observacional. Se incluyeron todos los casos de infección congénita por citomegalovirus desde 2003 hasta 2018 y se evaluaron las secuelas neurológicas a corto-medio plazo. Se compararon datos prenatales, perinatales y posnatales de los pacientes con secuelas neurológicas frente a los que no las presentaron. RESULTADOS: En el periodo descrito se registraron 60 pacientes con infección congénita por citomegalovirus: un 65% presentó afectación neurológica durante su periodo de seguimiento (retraso psicomotor 62,2%; microcefalia 61,5%, hipoacusia 46,2%; trastornos motores 27,8%; epilepsia 20,5% y coriorretinitis 5,6%). En el grupo de pacientes que presentó secuelas, la presencia de clínica en el periodo neonatal así como las alteraciones en el estudio de neuroimagen fueron más frecuentes y ambas fueron estadísticamente significativas respecto al grupo asintomático. Los pacientes con afectación neurológica también presentaron mayor puntuación en la escala de neuroimagen según Noyola et al. CONCLUSIONES: La sintomatología al nacimiento y ciertos hallazgos en la neuroimagen, como la presencia de alteraciones de la sustancia blanca o trastornos de la migración neuronal, podrían predecir las secuelas neurocognitivas en los pacientes con infección congénita por citomegalovirus

INTRODUCTION: The infection due to cytomegalovirus is the most common congenital infection in developed countries, and on of the main causes of psychomotor impairment and neurosensory hearing loss of infectious origin. The present study has its objectives to describe the clinical-analytical and neuroimaging of patients with secondary neurological sequelae secondary to the congenital cytomegalovirus infection and then compare them with the group of patients with a congenital cytomegalovirus infection that did not have neurological symptoms during their follow-up. MATERIAL AND METHODS: A retrospective, observational, cohort study was conducted that included all the cases of congenital cytomegalovirus infection from 2003 until 2018 and the short-medium term neurological sequelae were evaluated. Prenatal, perinatal, and postnatal data of patients with neurological sequelae were compared against those that did not present with any. RESULTS: A total of 60 patients with congenital cytomegalovirus infection were recorded during the study period, with 65% having neurological involvement during their follow-up period (62.2% with psychomotor impairment, 61.5% with microcephaly, 46.2% loss of hearing, 27.8% motor disorders, 20.5% epilepsy, and 5.6% with chorioretinitis). In the patient group that had sequelae, the presence of clinical symptoms during the neonatal period, as well as changes in the neuroimaging study, were the most common, with both being statistically significant compared to the asymptomatic group. The patients with neurological involvement also had a higher score on the Noyola et al. neuroimaging scale. CONCLUSIONS: The symptoms at birth, and certain findings in the neuroimaging, like the changes in the white matter or neuronal migration disorders, could predict neurocognitive sequelae in patients with congenital cytomegalovirus infection

[Neurological sequelae in patients with congenital cytomegalovirus]. / Secuelas neurológicas en pacientes con infección congénita por citomegalovirus.

INTRODUCTION: The infection due to cytomegalovirus is the most common congenital infection in developed countries, and on of the main causes of psychomotor impairment and neurosensory hearing loss of infectious origin. The present study has its objectives to describe the clinical-analytical and neuroimaging of patients with secondary neurological sequelae secondary to the congenital cytomegalovirus infection and then compare them with the group of patients with a congenital cytomegalovirus infection that did not have neurological symptoms during their follow-up. MATERIAL AND METHODS: A retrospective, observational, cohort study was conducted that included all the cases of congenital cytomegalovirus infection from 2003 until 2018 and the short-medium term neurological sequelae were evaluated. Prenatal, perinatal, and postnatal data of patients with neurological sequelae were compared against those that did not present with any. RESULTS: A total of 60 patients with congenital cytomegalovirus infection were recorded during the study period, with 65% having neurological involvement during their follow-up period (62.2% with psychomotor impairment, 61.5% with microcephaly, 46.2% loss of hearing, 27.8% motor disorders, 20.5% epilepsy, and 5.6% with chorioretinitis). In the patient group that had sequelae, the presence of clinical symptoms during the neonatal period, as well as changes in the neuroimaging study, were the most common, with both being statistically significant compared to the asymptomatic group. The patients with neurological involvement also had a higher score on the Noyola et al. neuroimaging scale. CONCLUSIONS: The symptoms at birth, and certain findings in the neuroimaging, like the changes in the white matter or neuronal migration disorders, could predict neurocognitive sequelae in patients with congenital cytomegalovirus infection.

[Hypomyelination with atrophy of the basal ganglia and cerebellum. Contribution of two new cases to a recently reported entity]. / Hipomielinización con atrofia de ganglios basales y de cerebelo. Aportación de dos nuevos casos a una entidad de descripción reciente.

INTRODUCTION: Hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC) is a rare condition that has only recently been reported. Here we present two new cases belonging to the same family. CASE REPORTS: Case 1: 17-month-old boy with severe underdevelopment in all areas, absence of language and eye contact. The examination revealed microcephaly with spastic tetraparesis. A magnetic resonance imaging scan showed predominantly vermian atrophy of the cerebellum with loss of volume of both nuclei of the putamen and the head of the caudate, and a pattern of hypomyelination of the white matter. Electromyography recording highlighted the presence of a predominantly motor pattern of chronic polyneuropathy. Homovallinic acid and 5-hydroxyindoleacetic acid values were lower than usual. Treatment with levodopa/carbidopa was not effective. Case 2: 11-month-old girl, the sister of the boy in the previous case. The patient presented severe underdevelopment in all areas and microcephaly with spastic tetraparesis was detected in the clinical examination. Magnetic resonance imaging of the head showed findings that could be superimposed upon those of the brother, with hypomyelination, cerebellar atrophy and involvement of the putamen and both caudates; electromyography findings were consistent with motor polyneuropathy of a demyelinating nature. Homovallinic acid and 5-hydroxyindoleacetic acid values in cerebrospinal fluid were lower than usual. Treatment with levodopa/carbidopa was ineffective. CONCLUSIONS: These two new cases help characterise this condition better and reinforce the hypothesis of the genetic origin of the syndrome, given that the two cases occurred in the same family.

TITLE: Hipomielinizacion con atrofia de ganglios basales y de cerebelo. Aportacion de dos nuevos casos a una entidad de descripcion reciente.Introduccion. La hipomielinizacion con atrofia de ganglios basales y de cerebelo (H-ABC) es una rara entidad descrita recientemente. Se presentan dos nuevos casos pertenecientes a una misma familia. Casos clinicos. Caso 1: niño de 17 meses con retraso grave en todas las areas, ausencia de lenguaje y de contacto visual. En la exploracion destacaba una microcefalia con tetraparesia espastica. En la resonancia magnetica cerebral se apreciaba atrofia cerebelosa de predominio vermiano con perdida de volumen de ambos nucleos del putamen y la cabeza del caudado, y patron de hipomielinizacion de la sustancia blanca. En la electromiografia se objetivo un patron de polineuropatia cronica de predominio motor. Presento un descenso de los valores de acido homovalinico y de acido 5-hidroxindolacetico. El tratamiento con levodopa/carbidopa no fue efectivo. Caso 2: niña de 11 meses, hermana del caso anterior. Presentaba un retraso grave en todas las areas y en la exploracion clinica se detecto una microcefalia con tetraparesia espastica. La resonancia magnetica cerebral mostro hallazgos superponibles a los del hermano, con hipomielinizacion, atrofia cerebelosa y afectacion putaminal y de ambos caudados; en la electromiografia, hallazgos compatibles con polineuropatia motora de caracter desmielinizante. Presento un descenso de los valores de acido homovalinico y acido 5-hidroxindolacetico en el liquido cefalorraquideo. El tratamiento con levodopa/carbidopa resulto ineficaz. Conclusiones. Estos dos nuevos casos ayudan a caracterizar mejor esta entidad y refuerzan la hipotesis del origen genetico del sindrome, dado que se trata de dos casos pertenecientes a una misma familia.

Hipomielinización con atrofia de ganglios basales y de cerebelo. Aportación de dos nuevos casos a una entidad de descripción reciente / Hypomyelination with atrophy of the basal ganglia and cerebellum. Contribution of two new cases to a recently reported entity

Introducción. La hipomielinización con atrofia de ganglios basales y de cerebelo (H-ABC) es una rara entidad descrita recientemente. Se presentan dos nuevos casos pertenecientes a una misma familia. Casos clínicos. Caso 1: niño de 17 meses con retraso grave en todas las áreas, ausencia de lenguaje y de contacto visual. En la exploración destacaba una microcefalia con tetraparesia espástica. En la resonancia magnética cerebral se apreciaba atrofia cerebelosa de predominio vermiano con pérdida de volumen de ambos núcleos del putamen y la cabeza del caudado, y patrón de hipomielinización de la sustancia blanca. En la electromiografía se objetivó un patrón de polineuropatía crónica de predominio motor. Presentó un descenso de los valores de ácido homovalínico y de ácido 5-hidroxindolacético. El tratamiento con levodopa/carbidopa no fue efectivo. Caso 2: niña de 11 meses, hermana del caso anterior. Presentaba un retraso grave en todas las áreas y en la exploración clínica se detectó una microcefalia con tetraparesia espástica. La resonancia magnética cerebral mostró hallazgos superponibles a los del hermano, con hipomielinización, atrofia cerebelosa y afectación putaminal y de ambos caudados; en la electromiografía, hallazgos compatibles con polineuropatía motora de carácter desmielinizante. Presentó un descenso de los valores de ácido homovalínico y ácido 5-hidroxindolacético en el líquido cefalorraquídeo. El tratamiento con levodopa/carbidopa resultó ineficaz. Conclusiones. Estos dos nuevos casos ayudan a caracterizar mejor esta entidad y refuerzan la hipótesis del origen genético del síndrome, dado que se trata de dos casos pertenecientes a una misma familia (AU)

Introduction. Hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC) is a rare condition that has only recently been reported. Here we present two new cases belonging to the same family. Case reports. Case 1: 17-month-old boy with severe underdevelopment in all areas, absence of language and eye contact. The examination revealed microcephaly with spastic tetraparesis. A magnetic resonance imaging scan showed predominantly vermian atrophy of the cerebellum with loss of volume of both nuclei of the putamen and the head of the caudate, and a pattern of hypomyelination of the white matter. Electromyography recording highlighted the presence of a predominantly motor pattern of chronic polyneuropathy. Homovallinic acid and 5-hydroxyindoleacetic acid values were lower than usual. Treatment with levodopa/carbidopa was not effective. Case 2: 11-month-old girl, the sister of the boy in the previous case. The patient presented severe underdevelopment in all areas and microcephaly with spastic tetraparesis was detected in the clinical examination. Magnetic resonance imaging of the head showed findings that could be superimposed upon those of the brother, with hypomyelination, cerebellar atrophy and involvement of the putamen and both caudates; electromyography findings were consistent with motor polyneuropathy of a demyelinating nature. Homovallinic acid and 5-hydroxyindoleacetic acid values in cerebrospinal fluid were lower than usual. Treatment with levodopa/carbidopa was ineffective. Conclusions. These two new cases help characterise this condition better and reinforce the hypothesis of the genetic origin of the syndrome, given that the two cases occurred in the same family (AU)