Exome sequencing of 20,979 individuals with epilepsy reveals shared and distinct ultra-rare genetic risk across disorder subtypes.

Identifying genetic risk factors for highly heterogeneous disorders like epilepsy remains challenging. Here, we present the largest whole-exome sequencing study of epilepsy to date, with >54,000 human exomes, comprising 20,979 deeply phenotyped patients from multiple genetic ancestry groups with diverse epilepsy subtypes and 33,444 controls, to investigate rare variants that confer disease risk. These analyses implicate seven individual genes, three gene sets, and four copy number variants at exome-wide significance.

Arginase 1 deficiency presenting as complicated hereditary spastic paraplegia.

Introduction: Argininemia or arginase deficiency is a metabolic disorder caused by pathogenic variants in ARG1 and consists of a variable association of progressive spastic paraplegia, intellectual disability, and seizures. Hereditary spastic paraplegia (HSP) is a group of inherited diseases whose main feature is a progressive gait disorder characterized by lower limb spasticity. This study presents 7 patients with arginase 1 deficiency from 6 different families, all with an initial diagnosis of complicated HSP.

Apraxia of Eyelid Opening and Blepharospasm in Two Spinocerebellar Ataxia Type 3 Patients.

Background: Neuroophthalmological phenotypical particularities of SCA3.

Phenomenology: Eyelid opening apraxia and asymmetrical blepharospasm.

Educational Value: To illustrate the phenomenology for purposes of education.

MECP2-related conditions in males: A systematic literature review and 8 additional cases.

Objective: To present a cohort of 8 males and perform a systematic review of all published cases with a single copy of MECP2 carrying a pathogenic variant.

Methods: We reviewed medical records of males with a single copy of MECP2 carrying a pathogenic variant. We searched in Medline (Pubmed) and Embase to collect all articles which included well-characterized males with a single copy of MECP2 carrying a pathogenic or likely pathogenic variant in MECP2 (1999-2020).

Additional observation of a de novo pathogenic variant in KCNT2 leading to epileptic encephalopathy with clinical features of frontal lobe epilepsy.

Introduction: KCNT2 was recently recognized as a gene associated with neurodevelopmental disorder and epilepsy.

Case Report: We present an additional observation of a 16-year-old male patient with a novel de novo KCNT2 likely pathogenic variant and review the five previously reported cases of de novo variants in this gene.

Discussion: Whole exome sequencing identified the missense variant c.

ATP6V1B2-related epileptic encephalopathy.

ATP6V1B2 encodes a subunit of the lysosomal transmembrane proton pump necessary for adequate functioning of several acid hydrolases. De novo monoallelic variants of this gene have been associated with two distinct phenotypes: Zimmermann-Laband syndrome 2 (ZLS2), an intellectual deficiency/multiple malformation syndrome, and dominant deafness onychodystrophy (DDOD), a multiple malformation syndrome without cognitive involvement. Epilepsy is not observed in DDOD, is variably present in ZLS2, but is a common feature in Zimmermann-Laband syndrome 1 (ZLS1) (caused by monoallelic pathogenic variants in KCNH1) and Zimmermann-Laband syndrome-like (ZLSL) (associated with KCNK4 variants).

Neurodevelopmental disorder associated with de novo SCN3A pathogenic variants: two new cases and review of the literature.

SCN3A was recently recognized as a gene associated with neurodevelopmental disorder and epilepsy. We present two additional patients with a novel de novo SCN3A pathogenic variant, and a review of all published cases of de novo variants. In one of our patients brain magnetic resonance imaging (MRI) disclosed a severe polymicrogyria and in the other it was normal.

A novel complex neurological phenotype due to a homozygous mutation in FDX2.

Defects in iron-sulphur [Fe-S] cluster biogenesis are increasingly recognized as causing neurological disease. Mutations in a number of genes that encode proteins involved in mitochondrial [Fe-S] protein assembly lead to complex neurological phenotypes. One class of proteins essential in the early cluster assembly are ferredoxins.

Pericytes Extend Survival of ALS SOD1 Mice and Induce the Expression of Antioxidant Enzymes in the Murine Model and in IPSCs Derived Neuronal Cells from an ALS Patient.

Amyotrophic Lateral Sclerosis (ALS) is one of the most common adult-onset motor neuron disease causing a progressive, rapid and irreversible degeneration of motor neurons in the cortex, brain stem and spinal cord. No effective treatment is available and cell therapy clinical trials are currently being tested in ALS affected patients. It is well known that in ALS patients, approximately 50% of pericytes from the spinal cord barrier are lost.

Clinical and genetic characterization of leukoencephalopathies in adults.

Leukodystrophies and genetic leukoencephalopathies are a rare group of disorders leading to progressive degeneration of cerebral white matter. They are associated with a spectrum of clinical phenotypes dominated by dementia, psychiatric changes, movement disorders and upper motor neuron signs. Mutations in at least 60 genes can lead to leukoencephalopathy with often overlapping clinical and radiological presentations.

Inferring paternal history of rural African-derived Brazilian populations from Y chromosomes.

Objectives: Quilombo remnants are relics of communities founded by runaway or abandoned African slaves, but often with subsequent extensive and complex admixture patterns with European and Native Americans. We combine a genetic study of Y-chromosome markers with anthropological surveys in order to obtain a portrait of quilombo structure and history in the region that has the largest number of quilombo remnants in the state of São Paulo.

Methods: Samples from 289 individuals from quilombo remnants were genotyped using a set of 17 microsatellites on the Y chromosome (AmpFlSTR-Yfiler).

Mutation in PNKP presenting initially as axonal Charcot-Marie-Tooth disease.

PNKP (polynucleotide kinase 3'-phosphatase, OMIM #605610) product is involved in the repair of strand breaks and base damage in the DNA molecule mainly caused by radical oxygen species. Deleterious variants affecting this gene have been previously associated with microcephaly, epilepsy, and developmental delay.(1) According to a previous report, homozygous loss-of-function substitution in PNKP was associated with cerebellar atrophy, neuropathy, microcephaly, epilepsy, and intellectual disability.

Overexpression of KLC2 due to a homozygous deletion in the non-coding region causes SPOAN syndrome.

SPOAN syndrome is a neurodegenerative disorder mainly characterized by spastic paraplegia, optic atrophy and neuropathy (SPOAN). Affected patients are wheelchair bound after 15 years old, with progressive joint contractures and spine deformities. SPOAN patients also have sub normal vision secondary to apparently non-progressive congenital optic atrophy.

Nerve conduction studies in spastic paraplegia, optic atrophy, and neuropathy (SPOAN) syndrome.

Introduction: SPOAN (spastic paraplegia, optic atrophy, and neuropathy) syndrome is an autosomal recessive neurodegenerative disorder identified in a large consanguineous Brazilian family.

Methods: Twenty-seven patients with SPOAN syndrome (20 women), aged 4-58 years, underwent nerve conduction studies (NCS) of the median, ulnar, tibial, and fibular nerves, and sensory NCS of the median, ulnar, radial, sural, and superficial fibular nerves.

Results: Sensory nerve action potentials were absent in the lower limbs and absent in >80% of upper limbs.

Motor and functional evaluation of patients with spastic paraplegia, optic atrophy, and neuropathy (SPOAN).

Spastic paraplegia, optic atrophy, and neuropathy (SPOAN) is an autosomal recessive complicated form of hereditary spastic paraplegia, which is clinically defined by congenital optic atrophy, infancy-onset progressive spastic paraplegia and peripheral neuropathy. In this study, which included 61 individuals (age 5-72 years, 42 females) affected by SPOAN, a comprehensive motor and functional evaluation was performed, using modified Barthel index, modified Ashworth scale, hand grip strength measured with a hydraulic dynamometer and two hereditary spastic paraplegia scales. Modified Barthel index, which evaluate several functional aspects, was more sensitive to disclose disease progression than the spastic paraplegia scales.

Spastic paraplegia, optic atrophy, and neuropathy: new observations, locus refinement, and exclusion of candidate genes.

SPOAN is an autosomal recessive neurodegenerative disorder which was recently characterized by our group in a large inbred Brazilian family with 25 affected individuals. This condition is clinically defined by: 1. congenital optic atrophy; 2.

Mutation in the Scyl1 gene encoding amino-terminal kinase-like protein causes a recessive form of spinocerebellar neurodegeneration.

Here, we show that the murine neurodegenerative disease mdf (autosomal recessive mouse mutant 'muscle deficient') is caused by a loss-of-function mutation in Scyl1, disrupting the expression of N-terminal kinase-like protein, an evolutionarily conserved putative component of the nucleocytoplasmic transport machinery. Scyl1 is prominently expressed in neurons, and enriched at central nervous system synapses and neuromuscular junctions. We show that the pathology of mdf comprises cerebellar atrophy, Purkinje cell loss and optic nerve atrophy, and therefore defines a new animal model for neurodegenerative diseases with cerebellar involvement in humans.