Expanded CGG-repeats have been linked to neurodevelopmental and neurodegenerative disorders, including the fragile X syndrome and fragile X-associated tremor/ataxia syndrome (FXTAS). We hypothesized that as of yet uncharacterised CGG-repeat expansions within the genome contribute to human disease. To catalogue the CGG-repeats, 544 human whole genomes were analyzed. In total, 6101 unique CGG-repeats were detected of which more than 93% were highly variable in repeat length. Repeats with a median size of 12 repeat units or more were always polymorphic but shorter repeats were often polymorphic, suggesting a potential intergenerational instability of the CGG region even for repeats units with a median length of four or less. 410 of the CGG repeats were associated with known neurodevelopmental disease genes or with strong candidate genes. Based on their frequency and genomic location, CGG repeats may thus be a currently overlooked cause of human disease.
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http://dx.doi.org/10.1038/s41598-021-82050-5 | DOI Listing |
Int J Mol Sci
December 2024
Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
(Fragile X messenger ribonucleoprotein 1), located on the X-chromosome, encodes the multi-functional FMR1 protein (FMRP), critical to brain development and function. Trinucleotide CGG repeat expansions at this locus cause a range of neurological disorders, collectively referred to as Fragile X-related conditions. The most well-known of these is Fragile X syndrome, a neurodevelopmental disorder associated with syndromic facial features, autism, intellectual disabilities, and seizures.
View Article and Find Full Text PDFInt J Mol Sci
December 2024
Department of Biochemistry and Molecular Medicine, School of Medicine, University of California Davis, Sacramento, CA 95817, USA.
Fragile X syndrome (FXS) is a genetic condition caused by the inheritance of alleles with >200 CGG repeats in the 5' UTR of the fragile X messenger ribonucleoprotein 1 () gene. These full mutation (FM) alleles are associated with DNA methylation and gene silencing, which result in intellectual disabilities, developmental delays, and social and behavioral issues. Mosaicism for both the size of the CGG repeat tract and the extent of its methylation is commonly observed in individuals with the FM.
View Article and Find Full Text PDFFragile X Syndrome (FXS) is characterized by intellectual impairment caused by CGG repeat expansion in the FMR1 gene. When repeats exceed 200, they induce DNA methylation of the promoter and the repeat region, resulting in transcriptional silencing of the FMR1 gene and the subsequent loss of FMRP protein. In the past decade or so, research has focused on the role of FMRP as an RNA-binding protein involved in translation inhibition in the brain in FXS model mice, particularly by slowing or stalling ribosome translocation on mRNA.
View Article and Find Full Text PDFInt J Mol Sci
November 2024
Department of Biomedicine, University of Basel, Mattenstrasse 28, 4058 Basel, Switzerland.
Fragile X Syndrome (FX) is the most common form of inherited cognitive impairment and falls under the broader category of Autism Spectrum Disorders (ASD). FX is caused by a CGG trinucleotide repeat expansion in the non-coding region of the X-linked () gene, leading to its hypermethylation and epigenetic silencing. Animal models of FX rely on the deletion of the gene, which fails to replicate the epigenetic silencing mechanism of the gene observed in human patients.
View Article and Find Full Text PDFFront Microbiol
November 2024
Department of Biology, University of Maragheh, Maragheh, Iran.
Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (CAS) genes make up bacteria's adaptive immune system against bacteriophages. In this study, 675 sequences of isolates deposited in GenBank were analyzed in terms of diversity, occurrence, and evolution of the CRISPR-Cas system. This study investigated the presence, structural variations, phylogenetic relationships, and diversity of CRISPR-Cas systems in 675 strains.
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