An understanding of spinocerebellar ataxia

Molecular spectrum, family screening and genetic counselling of Spinocerebellar Ataxia (SCA) cases in an Indian scenario

Spinocerebellar Ataxia (SCA) is a heterogeneous adult-onset disorder with an autosomal dominant inheritance pattern mainly caused by triplet repeat expansions. Clinical diagnosis of SCA is based on phenotypic features followed by confirmation through molecular diagnosis. To identify status of repeat range in Indian SCA cases and provide extended family screening, we enrolled 70 clinical SCA suspects. For molecular diagnosis, multiplex PCR (M-PCR) was used for common Indian SCA subtypes 1, 2, 3, 6, 7, 10, 12 and 17. TP-PCR was further used in SCA2, 7 and 10 to identify larger expansions. Eighteen out of 70 SCA suspects (25%) were found to be positive for various SCA subtypes- (5 SCA1 (28%), 6 SAC2 (34%), 2 SCA3 (12%), 3 SCA7 (16%) and one each for SCA6 (1%) and SCA17 (1%) subtypes). Genetic counselling and extended family screening were offered to all positive cases and yielded additional nine cases. We have established M-PCR and TP-PCR to detect the CAG repeat expansion in SCA suspects. This method can confirm SCA subtypes in a reliable, rapid and cost-effective way. Genetic characterization of SCA-related genes has great clinical relevance, as it could provide additional information and guidance to clinicians and family members regarding prognosis.

Spinocerebellar ataxia type 40: A case report and literature review

Spinocerebellar ataxias (SCAs) are a group of neurodegenerative diseases with ataxia as the main clinical manifestation. The phenotypes, gene mutations, and involved sites of different subtypes show a high degree of heterogeneity. The incidence of SCA varies greatly among different subtypes and the case of SCA40 is extremely rare. The aim of this study is to report a rare case of SCA40 and systematically review the incidence, gene mutation, and phenotype of SCAs, especially SCA40.

Do Post-Translational Modifications Influence Protein Aggregation in Neurodegenerative Diseases: A Systematic Review

The accumulation of abnormal protein aggregates represents a universal hallmark of neurodegenerative diseases (NDDs). Post-translational modifications (PTMs) regulate protein structure and function. Dysregulated PTMs may influence the propensity for protein aggregation in NDD-proteinopathies. To investigate this, we systematically reviewed the literature to evaluate effects of PTMs on aggregation propensity for major proteins linked to the pathogenesis and/or progression of NDDs. A search of PubMed, MEDLINE, EMBASE, and Web of Science Core Collection was conducted to retrieve studies that investigated an association between PTMs and protein aggregation in seven NDDs: Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), amyotrophic lateral sclerosis (ALS), spinocerebellar ataxias, transmissible spongiform encephalopathy, and multiple sclerosis. Together, 1222 studies were identified, of which 69 met eligibility criteria. We identified that the following PTMs, in isolation or combination, potentially act as modulators of proteinopathy in NDDs: isoaspartate formation in Aβ, phosphorylation of Aβ or tau in AD; acetylation, 4-hydroxy-2-neonal modification, O-GlcNAcylation or phosphorylation of α-synuclein in PD; acetylation or phosphorylation of TAR DNA-binding protein-43 in ALS, and SUMOylation of superoxide dismutase-1 in ALS; and phosphorylation of huntingtin in HD. The potential pharmacological manipulation of these aggregation-modulating PTMs represents an as-yet untapped source of therapy to treat NDDs.

Epigenetic profiles in polyglutamine disorders

The dominant polyglutamine (polyQ) disorders are a group of progressive and incurable neurodegenerative disorders, which are caused by unstable expanded CAG trinucleotide repeats in the coding regions of their respective causative genes. The most prevalent polyQ disorders worldwide are Huntington’s disease and spinocerebellar ataxia type 3. Epigenetic mechanisms, such as DNA methylation, histone modifications and chromatin remodeling and noncoding RNA regulation, regulate gene expression or genome function. Epigenetic dysregulation has been suggested to play a pivotal role in the pathogenesis of polyQ disorders. Here, we summarize the current knowledge of epigenetic changes present in several representative polyQ disorders and discuss the potentiality of miRNAs as therapeutic targets for the clinic therapy of these disorders.

Clinical Characteristics, Radiological Features and Gene Mutation in 10 Chinese Families with Spinocerebellar Ataxias

Background:

Spinocerebellar ataxias (SCAs) are a group of neurodegenerative disorders that primarily cause the degeneration in the cerebellum, spinal cord, and brainstem. We study the clinical characteristics, radiological features and gene mutation in Chinese families with SCAs.

Methods:

In this study, we investigated 10 SCAs Chinese families with SCA1, SCA3/Machado–Joseph disease (MJD), SCA7, SCA8. There were 27 people who were genetically diagnosed as SCA, of which 21 people showed clinical symptoms, and 6 people had no clinical phenotype that we called them presymptomatic patients. In addition, 3 people with cerebellar ataxia and cataracts were diagnosed according to the Harding diagnostic criteria but failed to be recognized as SCAs on genetic testing. Clinical characteristic analyses of each type of SCAs and radiological examinations were performed.

Results:

We found that SCA3/MJD was the most common subtype in Han population in China, and the ratio of the pontine tegmentum and the posterior fossa area was negatively correlated with the number of cytosine-adenine-guanine (CAG) repeats; the disease duration was positively correlated with the International Cooperative Ataxia Rating Scale score; and the CAG repeats number of abnormal alleles was negatively correlated with the age of onset.

Conclusions:

Collectively our study is a systematic research on SCAs in China, which may help for the clinical diagnosis and prenatal screening of this disease, and it may also aid toward better understanding of this disease.