Neurology. Genetics

BACKGROUND AND OBJECTIVES: Exome sequencing (ES) demonstrates a 20-50 percent diagnostic yield for patients with a suspected monogenic neurologic disease. Despite the proven efficacy in achieving a diagnosis for such patients, multiple barriers for obtaining exome sequencing remain. This study set out to assess the efficacy of ES in patients with primary neurologic phenotypes who were appropriate candidates for testing but had been unable to pursue clinical testing. METHODS: A total of 297 patients were identified from the UCLA Clinical Neurogenomics Research Center Biobank, and ES was performed, including bioinformatic assessment of copy number variation and repeat expansions...

BACKGROUND AND OBJECTIVES: Hexokinase 1 (encoded by HK1 ) catalyzes the first step of glycolysis, the adenosine triphosphate-dependent phosphorylation of glucose to glucose-6-phosphate. Monoallelic HK1 variants causing a neurodevelopmental disorder (NDD) have been reported in 12 individuals. METHODS: We investigated clinical phenotypes, brain MRIs, and the CSF of 15 previously unpublished individuals with monoallelic HK1 variants and an NDD phenotype. RESULTS: All individuals had recurrent variants likely causing gain-of-function, representing mutational hot spots...

OBJECTIVES: Mosaic gain of chromosome 1q (chr1q) has been associated with malformation of cortical development (MCD) and epilepsy. Hyaline protoplasmic astrocytopathy (HPA) is a rare neuropathologic finding seen in cases of epilepsy with MCD. The cell-type specificity of mosaic chr1q gain in the brain and the molecular signatures of HPA are unknown. METHODS: We present the case of a child with pharmacoresistant epilepsy who underwent epileptic focus resections at age 3 and 5 years and was found to have mosaic chr1q gain and HPA...

Neuronal intranuclear inclusion disease (NIID) is an underdiagnosed neurodegenerative disorder caused by pathogenic GGC expansions in NOTCH2NLC . However, an increasing number of reports of NOTCH2NLC GGC expansions in patients with Alzheimer disease, essential tremor, Parkinson disease, amyotrophic lateral sclerosis, and oculopharyngodistal myopathy have led to the proposal of a new concept known as NOTCH2NLC -related GGC repeat expansion disorders (NREDs). The majority of studies have mainly focused on screening for NOTCH2NLC GGC repeat variation in populations previously diagnosed with the associated disease, subsequently presenting it as a novel causative gene for the condition...

OBJECTIVES: Collagen VI-related myopathy spans a clinical continuum from severe Ullrich congenital muscular dystrophy to milder Bethlem myopathy, caused by genetic variants in COL6A1 , COL6A2 , and COL6A3 genes. Our objective was to report a newly identified patient with the pathogenic variants restricted to a polyadenylation signal in the 3'-untranslated region, which have not been reported in hereditary muscle disease. METHODS: We performed clinicopathologic diagnosis and analysis using whole-genome and RNA sequencing...

OBJECTIVES: Thymidine kinase 2 deficiency (TK2d) is a rare autosomal recessive disorder that stems from a perturbation of the mitochondrial DNA maintenance. Nucleoside treatment has recently shown promise as a disease-modifying therapy. TK2d was initially associated with rapidly progressive fatal myopathy in children featuring mitochondrial DNA depletion. Subsequently, less severe variants of the disease were described, with onset of symptoms during adolescence or adulthood and associated with the presence of multiple mtDNA deletions...

OBJECTIVES: To introduce the first case in which primary progressive apraxia of speech (PPAOS) is associated with TAR DNA-binding protein 43 (TDP-43) instead of 4-repeat tau. METHODS: This patient was identified through a postmortem autopsy. Following an initial diagnostic evaluation, he participated in 3 annual research visits during which speech, language, cognitive, and neurologic assessments were administered. Neuroimaging was also acquired. RESULTS: Apraxia of speech was diagnosed at his initial visit with a comprehensive neurologic examination further revealing subtle motor findings in the right hand...

OBJECTIVES: SLC6A1 -related disorders encompass heterogeneous neuropsychiatric manifestations through GABAergic dysregulation, without any specific abnormalities on brain MRI, nor evidence of dopaminergic cell loss on I123 -FP-β-CIT SPECT. We report here a case of globus pallidus lesions and dopaminergic denervation in a patient with a pathogenic SLC6A1 variant. METHODS: A 26-year-old female patient with intellectual disability, behavioral, and psychiatric disorders treated by neuroleptics for many years developed a parkinsonian syndrome associated with mild hand dystonia and chorea...

BACKGROUND AND OBJECTIVES: Pathogenic variants in PI3K-AKT-mTOR pathway and GATOR1 complex genes resulting in hyperactivation of mechanistic target of rapamycin (mTOR) complex 1 are a major cause of drug-resistant epilepsy and focal cortical malformations (FCM). Resective neurosurgery is often required to achieve seizure control in patients with mTORopathies due to lack of effectiveness of nonsurgical therapies, including antiseizure medication and mTOR inhibitors. Elevated hyperpolarization-activated cyclic nucleotide-gated potassium channel isoform 4 (HCN4) has been proposed as a key marker in some mTOR-related brain malformations...

OBJECTIVES: Characterize the presentation, workup, and management of SGCE myoclonus-dystonia, a rare genetic condition, in a patient with atypical presenting symptoms and no family history of movement abnormalities. METHODS: A woman with myoclonus and dystonia was identified based on clinical history and physical examination. Workup was conducted to determine the cause of her symptoms, including whole-exome sequencing. Myoclonus-dystonia is associated with more than 100 distinct mutations in MYC/DYT -SGCE that account for only half of the total myoclonus-dystonia patients...

BACKGROUND AND OBJECTIVES: Alzheimer disease (AD) has a polygenic architecture, for which genome-wide association studies (GWAS) have helped elucidate sequence variants (SVs) influencing susceptibility. Polygenic risk score (PRS) approaches show promise for generating summary measures of inherited risk for clinical AD based on the effects of APOE and other GWAS hits. However, existing PRS approaches, based on traditional regression models, explain only modest variation in AD dementia risk and AD-related endophenotypes...

BACKGROUND AND OBJECTIVES: Distal myopathies are a heterogeneous group of primary muscle disorders with recessive or dominant inheritance. ADSSL1 is a muscle-specific adenylosuccinate synthase isoform involved in adenine nucleotide synthesis. Recessive pathogenic variants in the ADSSL1 gene located in chromosome 14q32.33 cause a distal myopathy phenotype. In this study, we present the clinical and genetic attributes of 6 Indian patients with this myopathy. METHODS: This was a retrospective study describing on Indian patients with genetically confirmed ADSSL1 myopathy...

No abstract text is available yet for this article.

[This corrects the article DOI: 10.1212/NXG.0000000000200109.].

[This corrects the article DOI: 10.1212/NXG.0000000000200087.].

Cerebral cavernous malformations (CCMs) are vascular lesions characterized by a porous endothelium. The lack of a sufficient endothelial barrier can result in microbleeds and frank intracerebral hemorrhage. A primary mechanism for lesion development is a sequence variant in at least 1 of the 3 CCM genes ( CCM1 , CCM2 , and CCM3 ), which influence various signaling pathways that lead to the CCM phenotype. A common downstream process associated with CCM gene loss of function involves overactivation of RhoA and its effector Rho-associated kinase (ROCK)...

OBJECTIVES: Intellectual developmental disorder with speech delay, autism, and dysmorphic facies (IDDSADF) is caused by heterozygous CNOT3 (MIM# 604910) variants on chromosome 19q13. This study aimed to identify and describe the clinical features of a Korean family with maternally inherited speech delay and intellectual and developmental disability to elucidate the underlying genetic mechanism. METHODS: We conducted whole-exome sequencing and confirmatory Sanger sequencing on the proband, the mother, and unaffected grandparents with wild-type genotypes...

OBJECTIVES: To investigate the etiology of cerebellar ataxia in an adult male patient. METHODS: We performed standard neurologic assessment and genome sequencing of a 62-year-old man with rapidly progressive balance and gait abnormalities. RESULTS: The propositus exhibited cognitive dysfunction, mild appendicular bradykinesia, prominent appendicular ataxia, dysarthria, and hypomimia with minimal dysautonomic symptoms. Nerve conduction studies showed mild peripheral sensory neuropathy and normal motor nerve conduction velocities...

OBJECTIVES: Paroxysmal ataxia is typically characterized by early-onset attacks of cerebellar ataxia. Late-onset cerebellar ataxia (LOCA) comprises a group of neurodegenerative disorders mainly characterized by adult-onset progressive cerebellar ataxia. A deep intronic expansion of a GAA triplet in the FGF14 gene encoding fibroblast growth factor 14 has recently been identified as a frequent cause of LOCA. METHODS: We describe a patient with paroxysmal ataxia/dysarthria due to a FGF14 repeat expansion and 3 affected family members...

BACKGROUND AND OBJECTIVES: Evidence suggests that either family history or polygenic risk score (PRS) is associated with developing Parkinson disease (PD). However, little is known about the longitudinal prognosis of PD according to family history and higher PRS. METHODS: From the Parkinson's Progression Markers Initiative database, 395 patients with PD who followed up for more than 2 years were grouped into those with family history within first-degree, second-degree, and third-degree relatives (N = 127 [32...