This finding confirms that the fragile X phenotype can exist, without amplification of the CCG repeat or cytogenetic expression of the fragile X, and that fragile X syndrome is a genetically homogeneous disorder involving FMR1.
These recombination events were used to define the position of Fmr-1, the murine homologue of FMR1, which is the gene implicated in the fragile X syndrome in man, and that of DXS296h, the murine homologue of DXS296.
The fragile X [fra(X)] syndrome is the most frequent form of inherited mental retardation, and co-segregates with a fragile site at Xq27.3 as well as with insertion of a variable number of trinucleotide repeats in the 5'-end of the FMR-1 gene.
Identification of a gene (FMR-1) containing a CGG repeat coincident with a breakpoint cluster region exhibiting length variation in fragile X syndrome.
Localization of the brain-expressed FMR-1 gene to this EcoRI fragment suggests the involvement of this gene in the phenotypic expression of the fragile X syndrome.
To study the involvement of the FMR-1 gene in the fragile X syndrome, its expression was studied in lymphoblastoid cell lines and leukocytes derived from patients and normal controls.
These findings suggest that the FMR-1 mutation causing the fragile X syndrome leads to observable changes in neuroanatomy that may be relevant to the neurodevelopmental disability and behavioural problems observed in affected individuals.
The molecular mechanism of the fragile X syndrome is based on the expansion of an CGG repeat in the 5' UTR of the FMR1 gene in the majority of fragile X patients.
We report here the identification of two different intragenic loss of function mutations in FMR1: a single de novo nucleotide deletion in a young male patient (IJ) and an inherited two basepair change in an Adult male (SD), each with classical features of fragile X syndrome.
We report here the identification of two different intragenic loss of function mutations in FMR1: a single de novo nucleotide deletion in a young male patient (IJ) and an inherited two basepair change in an Adult male (SD), each with classical features of fragile X syndrome.