FMRP loss is phenocopied by conditional removal of FMRP only during this critical period, and rescued by FMRP conditional expression only during this critical period.
Here we demonstrate the creation of a robust FMR1-Nluc reporter hiPSC line by knocking in a Nano luciferase (Nluc) gene into the endogenous human FMR1 gene using the CRISPR/Cas9 genome editing method.
Importantly, we validated that elevating neural network activity requires protein translation and is dependent on fragile X mental retardation protein (FMRP), the protein that is deficient in the most common inherited form of mental retardation and autism, fragile X syndrome (FXS).
We utilized a sample of 299 adult females aged between 19 and 86 years, carrying fragile X mental retardation (FMR1) alleles with small CCG expansions ranging from 50 to 141 repeats to analyse the relationships between psychological symptoms as assessed by the Symptom Checklist-90-Revised (SCL-90-R) and the size of the CGG repeat in the FMR1 gene.
Missense mutations in the FMR1 gene might account for a considerable proportion of cases in male patients with FXS-related symptoms, such as those linked to mental retardation and developmental delay.
In fragile X syndrome, the most common genetic form of mental retardation, a CGG trinucleotide-repeat expansion adjacent to the fragile X mental retardation 1 (FMR1) gene promoter results in its epigenetic silencing.
Fragile X Syndrome (FXS), the most common inherited form of mental retardation, is caused by expansion of a CGG/CCG repeat tract in the 5'-untranslated region of the fragile X mental retardation (FMR1) gene, which changes the functional organization of the gene from euchromatin to heterochromatin.
Fragile X Syndrome (FXS), the most common cause of familiar mental retardation, is associated in over 99% of cases to an expansion over 200 repeats of a CGG sequence in the 5' UTR of the FMR1 gene (Xq27.3), leading to the hypermethylation of the promoter.
Fragile X syndrome, the leading inherited cause of mental retardation and autism spectrum disorders worldwide, is caused by a tandem repeat expansion in the FMR1 (fragile X mental retardation 1) gene.
Despite the known relationship between FMR1 CGG repeat expansion and FMR1 silencing, the epigenetic modifications observed at the FMR1 locus, and the consequences of the loss of FMRP on human neurodevelopment and neuronal function remain poorly understood.
Methylation of both regions was correlated with that of the FMR1 CpG island detected using Southern blot (FREE1 R = 0.97; P < 0.00001, n = 23 and FREE2 R = 0.93; P < 0.00001, n = 23) and negatively correlated with lymphocyte expression of FMRP (FREE1 R = -0.62; P = 0.01, n = 15 and FREE2 R = -0.55; P = 0.03, n = 15) in blood of partially methylated 'high functioning' FM males.
We present a family with one patient with mild mental retardation who showed an atypical profile at Southern analysis due to the -413C > G transversion located in the FMR1 promoter which had been described as possibly associated with mental retardation.
Fragile X syndrome is a common inherited cause of mental retardation that results from loss or mutation of the fragile X mental retardation protein (FMRP).
We review the literature of FMR1 deletions and present this case in the context of other FMR1 deletions having mental retardation that may or may not have the classic fragile X phenotype.
Fragile X syndrome is the most common cause of inherited mental retardation; it is caused by expansion of CGG repeats in the first exon of the FMR1 gene.
The fragile X syndrome (FRAXA) is the most widespread heritable form of mental retardation caused by the lack of expression of the fragile X mental retardation protein (FMRP).