The human genome has many short tandem repeats, yet the normal functions of these repeats are unclear. The 5' untranslated region (UTR) of the fragile X messenger ribonucleoprotein 1 (FMR1) gene contains polymorphic CGG repeats, the length of which has differing effects on FMR1 expression and human health, including the neurodevelopmental disorder fragile X syndrome. We deleted the CGG repeats in the FMR1 gene (0CGG) in human stem cells and examined the effects on differentiated neurons. 0CGG neurons have altered subcellular localization of FMR1 mRNA and protein, and differential expression of cellular stress proteins compared with neurons with normal repeats (31CGG). In addition, 0CGG neurons have altered responses to glucocorticoid receptor (GR) activation, including FMR1 mRNA localization, GR chaperone HSP90α expression, GR localization, and cellular stress protein levels. Therefore, the CGG repeats in the FMR1 gene are important for the homeostatic responses of neurons to stress signals.
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http://dx.doi.org/10.1016/j.celrep.2024.114330 | DOI Listing |
Int J Mol Sci
January 2025
Department of Women's and Children's Health, University of Padova, 35128 Padova, Italy.
Fragile X syndrome (FXS) is a genetic neurodevelopmental disorder that causes a range of developmental problems including cognitive and behavioral impairment and learning disabilities. FXS is caused by full mutations (FM) of the gene expansions to over 200 repeats, with hypermethylation of the cytosine-guanine-guanine (CGG) tandem repeated region in its promoter, resulting in transcriptional silencing and loss of gene function. Female carriers of FM are typically less impaired than males.
View Article and Find Full Text PDFMov Disord
January 2025
British Columbia Children's Hospital Research Institute, Vancouver, British Columbia, Canada.
Background: Trinucleotide repeat expansions are an emerging class of genetic variants associated with various movement disorders. Unbiased genome-wide analyses can reveal novel genotype-phenotype associations and provide a diagnosis for patients and families.
Objective: The aim was to identify the genetic cause of a severe progressive movement disorder phenotype in 2 affected brothers.
Case Rep Genet
January 2025
Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California, 2825 50th Street, Davis, Sacramento 95817, California, USA.
Fragile X syndrome (FXS) presents with autism spectrum disorder (ASD), intellectual disability, developmental delay, seizures, hypotonia during infancy, joint laxity, behavioral issues, and characteristic facial features. The predominant mechanism is due to CGG trinucleotide repeat expansion of more than 200 repeats in the 5'UTR (untranslated region) of (Fragile X Messenger Ribonucleoprotein 1) causing promoter methylation and transcriptional silencing. However, not all patients presenting with the characteristic phenotype and point/frameshift mutations with deletions in have been described in the literature.
View Article and Find Full Text PDFSci Rep
January 2025
Reproductive Medicine Center, Jiangxi Maternal and Child Health Hospital, 318 Bayi Avenue, Nanchang, 330006, China.
To explore the genetic cause of a four-generation severe intellectual disability in a Chinese family using nanopore sequencing and to provide genetic counseling and reproductive guidance for family members. Multiple genetic analyses of the proband and family members were performed, including chromosome karyotype analysis, whole exome sequencing, nanopore sequencing, PCR amplification, and Sanger sequencing. The results of G-binding karyotyping, CGG repeats for FMR1, GGC repeats for NOTCH2NCL, and trio-whole-exome sequencing were negative for the proband and his parents.
View Article and Find Full Text PDFInt 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.
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