Diagnostic yield and limitations of whole-genome sequencing for hereditary cerebellar ataxia.

Less than half of the individuals with hereditary cerebellar ataxia receives a genetic diagnosis. Repeat expansions account for disproportionate number of hereditary cerebellar ataxia and have genetically heterogeneous causes. These genetic loci include , , , , , , , , , and This study aims to assess the yield of short-read whole genome sequencing in the molecular diagnosis of hereditary cerebellar ataxia.

A genome-wide approach for the discovery of novel repeat expansion disorders in the Undiagnosed Diseases Network cohort.

Purpose: The Undiagnosed Diseases Network is a National Institutes of Health funded research study that aims to solve a broad clinical spectrum of challenging rare disease cases. Participants receive care from multiple clinical specialists, who collaborate to perform deep phenotyping and state-of-the-art multiomics analyses. As bioinformatics of short-read sequencing has matured, the discovery of repeat expansion disorders (REDs) is accelerating.

Intronic FGF14 GAA repeat expansions impact progression and survival in multiple system atrophy.

Partial phenotypic overlap has been suggested between multiple system atrophy and spinocerebellar ataxia 27B, the autosomal dominant ataxia caused by an intronic GAA•TTC repeat expansion in FGF14. In this study, we investigated the frequency of FGF14 GAA•TTC repeat expansion in clinically diagnosed and pathologically confirmed multiple system atrophy cases. We screened 657 multiple system atrophy cases (193 clinically diagnosed and 464 pathologically confirmed) and 1003 controls.

The continued promise of genomic technologies and software in neurogenetics.

The continued evolution of genomic technologies over the past few decades has revolutionized the field of neurogenetics, offering profound insights into the genetic underpinnings of neurological disorders. Identification of causal genes for numerous monogenic neurological conditions has informed key aspects of disease mechanisms and facilitated research into critical proteins and molecular pathways, laying the groundwork for therapeutic interventions. However, the question remains: has this transformative trend reached its zenith? In this review, we suggest that despite significant strides in genome sequencing and advanced computational analyses, there is still ample room for methodological refinement.

FGF14 GAA Intronic Expansion in Unsolved Adult-Onset Ataxia in the Care4Rare Canada Consortium.

Background And Objectives: Spinocerebellar ataxias (SCA) represent a clinically and genetically heterogeneous group of progressive neurodegenerative diseases with prominent cerebellar atrophy. Recently, a novel pathogenic repeat expansion in intron 1 of FGF14 was identified, causing adult-onset SCA (SCA27B). We aimed to determine the proportion of our unsolved adult-onset ataxia cohort harboring this expansion using several technologies, and to characterize the phenotypic presentation within our population.

Late-onset vestibulocerebellar ataxia: clinical and genetic studies in a long follow-up series of 50 patients.

Background: To describe the epidemiology, clinical features, degree of disability and genetic characteristics of a cohort of patients with a vestibulo-cerebellar ataxia of very late onset (LOVCA).

Methods: We analysed the clinical, radiological, and genetic characteristics of a cohort of 50 patients with LOVCA. Where possible, patients were followed over the full course of the disease, including clinical, and molecular genetic analysis of genes known to cause episodic ataxia.

The Spastic Paraplegia-Centers of Excellence Research Network (SP-CERN): Clinical Trial Readiness for Hereditary Spastic Paraplegia.

Objectives: The primary objective of this paper was to present the establishment of the Spastic Paraplegia-Centers of Excellence Research Network (SP-CERN) aimed at promoting clinical trial readiness for hereditary spastic paraplegia (HSP). SP-CERN is unique in its approach to addressing the diagnostic and therapeutic challenges associated with HSP through a large-scale, collaborative effort.

Methods: Participants with HSP are identified through multicenter collaborations across 11 institutions in the United States.

Involvement of the Superior Cerebellar Peduncles in GAA- Ataxia.

Objectives: GAA- ataxia (SCA27B) is a recently reported late-onset ataxia caused by a GAA repeat expansion in intron 1 of the gene. After the clinical observation of superior cerebellar peduncle (SCP) involvement in some affected patients, we sought to verify the prevalence of this finding in our cohort and 4 additional independent cohorts of patients with SCA27B.

Methods: We performed a retrospective review of the brain MRI scans of a total of 87 patients (median age at MRI 69 years; range 28-88 years) from different independent cohorts to assess the presence of SCP involvement, defined as abnormally high T2 signal along the SCP tract.

Detailed tandem repeat allele profiling in 1,027 long-read genomes reveals genome-wide patterns of pathogenicity.

Tandem repeats are a highly polymorphic class of genomic variation that play causal roles in rare diseases but are notoriously difficult to sequence using short-read techniques. Most previous studies profiling tandem repeats genome-wide have reduced the description of each locus to the singular value of the length of the entire repetitive locus. Here we introduce a comprehensive database of 3.

Recent Advances in the Genetics of Ataxias: An Update on Novel Autosomal Dominant Repeat Expansions.

Purpose Of Review: Autosomal dominant cerebellar ataxias, also known as spinocerebellar ataxias (SCAs), are genetically and clinically diverse neurodegenerative disorders characterized by progressive cerebellar dysfunction. Despite advances in sequencing technologies, a large proportion of patients with SCA still lack a definitive genetic diagnosis. The advent of advanced bioinformatic tools and emerging genomics technologies, such as long-read sequencing, offers an unparalleled opportunity to close the diagnostic gap for hereditary ataxias.

Screening for SCA27B, CANVAS and other repeat expansion disorders in Greek patients with late-onset cerebellar ataxia suggests a need to update current diagnostic algorithms.

Objective: Late-onset cerebellar ataxia (LOCA) is a slowly progressive cerebellar disorder with symptom onset ≥30years of age. Intronic tandem repeat expansions (TREs) in RFC1 and FGF14 have recently emerged as common causes of LOCA. The relative contribution of classic vs.

Customized antisense oligonucleotide-based therapy for neurofilament-associated Charcot-Marie-Tooth disease.

DNA-based therapeutics have emerged as a revolutionary approach for addressing the treatment gap in rare inherited conditions by targeting the fundamental genetic causes of disease. Charcot-Marie-Tooth (CMT) disease, a group of inherited neuropathies, represents one of the most prevalent Mendelian disease groups in neurology and is characterized by diverse genetic aetiology. Axonal forms of CMT, known as CMT2, are caused by dominant mutations in >30 different genes that lead to degeneration of lower motor neuron axons.

A recurrent missense variant in ITPR3 causes demyelinating Charcot-Marie-Tooth with variable severity.

Charcot-Marie-Tooth (CMT) disease is a neuromuscular disorder affecting the peripheral nervous system. The diagnostic yield in demyelinating CMT (CMT1) is typically ∼80%-95%, of which at least 60% is due to the PMP22 gene duplication. The remainder of CMT1 is more genetically heterogeneous.

Neurological disorders caused by novel non-coding repeat expansions: clinical features and differential diagnosis.

Nucleotide repeat expansions in the human genome are a well-known cause of neurological disease. In the past decade, advances in DNA sequencing technologies have led to a better understanding of the role of non-coding DNA, that is, the DNA that is not transcribed into proteins. These techniques have also enabled the identification of pathogenic non-coding repeat expansions that cause neurological disorders.

A study concept of expeditious clinical enrollment for genetic modifier studies in Charcot-Marie-Tooth neuropathy 1A.

Background: Caused by duplications of the gene encoding peripheral myelin protein 22 (PMP22), Charcot-Marie-Tooth disease type 1A (CMT1A) is the most common hereditary neuropathy. Despite this shared genetic origin, there is considerable variability in clinical severity. It is hypothesized that genetic modifiers contribute to this heterogeneity, the identification of which may reveal novel therapeutic targets.