8 research outputs found
ATAXIN2 CAG-repeat length in Italians patients with amyotrophic lateral sclerosis : risk factor or variant phenotype? Implication for genetic testing and counseling
No full textAmyotrophic lateral sclerosis (ALS) is a neurodegenerative disease mainly involving cortical and spinal motor neurons. Several studies indicated that intermediate CAG expansions in ataxin-2 gene (. ATXN2) are associated with increased risk of ALS. We analyzed . ATXN2 CAG repeats in 658 sporadic ALS patients (SALS), 143 familial ALS cases (FALS), 231 sporadic ataxic subjects, and 551 control subjects. The frequency of . ATXN2 alleles with 27-30 repeats was similar in SALS and control subjects. Fifteen SALS subjects carried ≥ 31 CAG repeats. This difference was statistically significant (. p = 0.0014). No alleles with ≥ 34 CAG were found. In FALS, the distribution of . ATXN2 alleles was similar to control subjects. Our results further contributed in refining CAG-repeat range significantly associated with sporadic ALS. Literature data and our findings indicate that only alleles with ≥ 31 CAG may represent low-penetrance disease/susceptibility alleles associated with variable neurodegenerative phenotypes, including cerebellar ataxia, parkinsonism, and ALS. Overlapping phenotypes should be considered in genetic testing and counseling, both for patients and at-risk family members
Mutational analysis of VCP gene in familial amyotrophic lateral sclerosis
No full textA hexanucleotide repeat expansion (RE) in C9ORF72 gene was recently reported as the main cause of amyotrophic lateral sclerosis (ALS) and cases with frontotemporal dementia. We screened C9ORF72 in a large cohort of 259 familial ALS, 1275 sporadic ALS, and 862 control individuals of Italian descent. We found RE in 23.9% familial ALS, 5.1% sporadic ALS, and 0.2% controls. Two cases carried the RE together with mutations in other ALS-associated genes. The phenotype of RE carriers was characterized by bulbar-onset, shorter survival, and association with cognitive and behavioral impairment. Extrapyramidal and cerebellar signs were also observed in few patients. Genotype data revealed that 95% of RE carriers shared a restricted 10-single nucleotide polymorphism haplotype within the previously reported 20-single nucleotide polymorphism risk haplotype, detectable in only 27% of nonexpanded ALS cases and in 28% of controls, suggesting a common founder with cohorts of North European ancestry. Although C9ORF72 RE segregates with disease, the identification of RE both in controls and in patients carrying additional pathogenic mutations suggests that penetrance and phenotypic expression of C9ORF72 RE may depend on additional genetic risk factors. (C) 2012 Elsevier Inc. All rights reserved
The first reported generation of several induced pluripotent stem cell lines from homozygous and heterozygous Huntington’s disease patients demonstrates mutation related enhanced lysosomal activity
No full textNeuronal disorders, like Huntington's disease (HD), are difficult to study, due to limited cell accessibility, late onset manifestations, and low availability of material. The establishment of an in vitro model that recapitulates features of the disease may help understanding the cellular and molecular events that trigger disease manifestations. Here, we describe the generation and characterization of a series of induced pluripotent stem (iPS) cells derived from patients with HD, including two rare homozygous genotypes and one heterozygous genotype. We used lentiviral technology to transfer key genes for inducing reprogramming. To confirm pluripotency and differentiation of iPS cells, we used PCR amplification and immunocytochemistry to measure the expression of marker genes in embryoid bodies and neurons. We also analyzed teratomas that formed in iPS cell-injected mice. We found that the length of the pathological CAG repeat did not increase during reprogramming, after long term growth in vitro, and after differentiation into neurons. In addition, we observed no differences between normal and mutant genotypes in reprogramming, growth rate, caspase activation or neuronal differentiation. However, we observed a significant increase in lysosomal activity in HD-iPS cells compared to control iPS cells, both during self-renewal and in iPS-derived neurons.In conclusion, we have established stable HD-iPS cell lines that can be used for investigating disease mechanisms that underlie HD. The CAG stability and lysosomal activity represent novel observations in HD-iPS cells. In the future, these cells may provide the basis for a powerful platform for drug screening and target identification in HD
Molecular mechanism of Spinocerebellar Ataxia type 6: glutamine repeat disorder, channelopathy and transcriptional dysregulation. The multifaceted aspects of a single mutation.
No full textSpinocerebellar Ataxia type 6 (SCA6) is an autosomal dominant neurodegenerative disease characterized by late onset, slowly progressive, mostly pure cerebellar ataxia. It is one of three allelic disorders associated to CACNA1A gene, coding for the Alpha1 A subunit of P/Q type calcium channel Cav2.1 expressed in the brain, particularly in the cerebellum. The other two disorders are Episodic Ataxia type 2 (EA2), and Familial Hemiplegic Migraine type 1 (FHM1). These disorders show distinct phenotypes that often overlap but have different pathogenic mechanisms. EA2 and FHM1 are due to mutations causing, respectively, a loss and a gain of channel function. SCA6, instead, is associated with short expansions of a polyglutamine stretch located in the cytoplasmic C-terminal tail of the protein. This domain has a relevant role in channel regulation, as well as in transcription regulation of other neuronal genes; thus the SCA6 CAG repeat expansion results in complex pathogenic molecular mechanisms reflecting the complex Cav2.1 C-terminus activity. We will provide a short review for an update on the SCA6 molecular mechanism
The first reported generation of several induced pluripotent stem cell lines from homozygous and heterozygous Huntington's disease patients demonstrates mutation related enhanced lysosomal activity
No full textNovel cell models for the study of spinocerebellar ataxia type 7 pathogenesis and therapy in a South African patient cohort
No full textIncludes abstract.Includes bibliographical references.Spinocerebellar ataxia type 7 (SCA7) is a dominantly-inherited neurodegenerative disease, resulting from a CAG trinucleotide repeat expansion in the ataxin-7 gene. The Ataxin-7 protein is known to play a role in transcriptional regulation through association with cellular histone acetylation complexes, and several studies have highlighted the role of transcriptional dysregulation, caused by the presence of mutant Ataxin-7, in the neuronal dysfunction that precedes the onset of disease symptoms.This study aimed to establish patient-derived cell models of SCA7, for use in the investigation of pathogenesis (with particular reference to transcriptional alterations), and in the evaluation of previously-developed therapies for the disease.The high prevalence of SCA7 in the South African population, as a result of a founder effect, makes this disease particularly amenable to allele-specific RNA interference (RNAi)-based therapy. Thus, this study also evaluated the feasibility of these cell models as a vehicle to test previously-developed RNAi therapeutics, using the alteration of expression of key transcripts as a phenotypic marker. SCA7 patient and control dermal fibroblasts were reprogrammed to pluripotency by retroviral transduction. The resultant induced pluripotent stem cell (iPSC) lines were characterised with respect to endogenous markers of pluripotency, differentiation capacity and transgene silencing. These cells were then subjected to neuronal differentiation, the success of which was confirmed by the expression of early neuronal markers
