Browsing by Author "Lee, Virginia M.-Y."

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    Absence of C9ORF72 expanded or intermediate repeats in autopsy-confirmed Parkinson's disease
    (Wiley, 2014-05) Nuytemans, Karen; Inchausti, Vanessa; Beecham, Gary W.; Wang, Liyong; Dickson, Dennis W.; Trojanowski, John Q.; Lee, Virginia M.-Y.; Mash, Deborah C.; Frosch, Matthew P.; Foroud, Tatiana M.; Honig, Lawrence S.; Montine, Thomas J.; Dawson, Ted M.; Martin, Eden R.; Scott, William K.; Vance, Jeffery M.; Medical & Molecular Genetics, School of Medicine
    BACKGROUND: We have reported that intermediate repeat lengths of the C9ORF72 repeat are a risk factor for Parkinson's disease (PD) in a clinically diagnosed data set. Because 10% to 25% of clinically diagnosed PD have different diagnoses upon autopsy, we hypothesized that this may reflect phenotypic heterogeneity or concomitant pathology of other neurodegenerative disorders. METHODS: We screened 488 autopsy-confirmed PD cases for expansion haplotype tag rs3849942T. In 196 identified haplotype carriers, the C9ORF72 repeat was genotyped using the repeat-primed polymerase chain reaction assay. RESULTS: No larger (intermediate or expanded) repeats were found in these autopsy-confirmed PD samples. This absence of larger repeats is significantly different from the frequency in clinically diagnosed datasets (P = 0.002). CONCLUSIONS: Our results suggest that expanded or intermediate C9ORF72 repeats in clinically diagnosed PD or parkinsonism might be an indication of heterogeneity in clinically diagnosed PD cases. Further studies are needed to elucidate the potential contribution of the C9ORF72 repeat to autopsy-confirmed PD.
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    C9orf72 Intermediate Repeats are Associated with Corticobasal Degeneration, Increased C9orf72 Expression and Disruption of Autophagy
    (Springer, 2019-11) Cali, Christopher P.; Patino, Maribel; Tai, Yee Kit; Ho, Wan Yun; McLean, Catriona A.; Morris, Christopher M.; Seeley, William W.; Miller, Bruce L.; Gaig, Carles; Vonsattel, Jean Paul G.; White, Charles L.; Roeber, Sigrun; Kretzschmar, Hans; Troncoso, Juan C.; Troakes, Claire; Gearing, Marla; Ghetti, Bernardino; Van Deerlin, Vivianna M.; Lee, Virginia M.-Y.; Trojanowski, John Q.; Mok, Kin Y.; Ling, Helen; Dickson, Dennis W.; Schellenberg, Gerard D.; Ling, Shuo-Chien; Lee, Edward B.; Pathology and Laboratory Medicine, School of Medicine
    Microsatellite repeat expansion disease loci can exhibit pleiotropic clinical and biological effects depending on repeat length. Large expansions in C9orf72 (100s-1000s of units) are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal degeneration (FTD). However, whether intermediate expansions also contribute to neurodegenerative disease is not well understood. Several studies have identified intermediate repeats in Parkinson’s disease patients, but the association was not found in autopsy confirmed cases. We hypothesized that intermediate C9orf72 repeats are a genetic risk factor for corticobasal degeneration (CBD), a neurodegenerative disease that can be clinically similar to Parkinson’s but has distinct tau protein pathology. Indeed, intermediate C9orf72 repeats were significantly enriched in autopsy-proven CBD (n=354 cases, odds ratio=3.59, p-value=0.00024). While large C9orf72 repeat expansions are known to decrease C9orf72 expression, intermediate C9orf72 repeats result in increased C9orf72 expression in human brain tissue and CRISPR/cas9 knockin iPSC derived neural progenitor cells. In contrast to cases of FTD/ALS with large C9orf72 expansions, CBD with intermediate C9orf72 repeats was not associated with pathologic RNA foci or dipeptide repeat protein aggregates. Knock-in cells with intermediate repeats exhibit numerous changes in gene expression pathways relating to vesicle trafficking and autophagy. Additionally, overexpression of C9orf72 without the repeat expansion leads to defects in autophagy under nutrient starvation conditions. These results raise the possibility that therapeutic strategies to reduce C9orf72 expression may be beneficial for the treatment of CBD.