Identification of a gene (FMR-1) containing a CGG repeat coincident with a breakpoint cluster region exhibiting length variation in fragile X syndrome

  title={Identification of a gene (FMR-1) containing a CGG repeat coincident with a breakpoint cluster region exhibiting length variation in fragile X syndrome},
  author={Annemieke J M H Verkerk and Maura Pieretti and James S. Sutcliffe and Ying-Hui Fu and Derek P.A. Kuhl and Antonio Pizzuti and Orly Reiner and Stephen Richards and Maureen F. Victoria and Fuping Zhang and Bert E. Eussen and G. J. B. Ommen and Lau A.J. Blonden and Gregory J Riggins and Jane L. Chastain and Catherine B. Kunst and Hans J.C. Galjaard and Charles Thomas Caskey and David L Nelson and Ben A. Oostra and Stephen T. Warren},

A microdeletion of less than 250 kb, including the proximal part of the FMR-I gene and the fragile-X site, in a male with the clinical phenotype of fragile-X syndrome.

Evidence is presented that a deletion including the HTF island and exons of the FMR-1 gene was detected in a fragile X-negative mentally retarded male who presented the clinical phenotype of the fragile-X syndrome.

Characterization and localization of the FMR-1 gene product associated with fragile X syndrome

The nature and function of the protein encoded by the FMR-1 gene is investigated using polyclonal antibodies raised against the predicted amino-acid sequences and four different protein products, possibly resulting from alternative splicing, have been identified by immunoblotting in lymphoblastoid cell lines of healthy individuals.

Rare variants in the promoter of the fragile X syndrome gene (FMR1).

Two different changes (a C to G substitution at -149 and a GGC insertion at -154) in the promoter of the FMR1 gene are identified, the first variants described in the promoters of theFMR1 genes.

A point mutation in the FMR-1 gene associated with fragile X mental retardation

The results suggest that mutations in FMR–1 are directly responsible for fragile X syndrome, irrespective of possible secondary effects caused by FRAXA.

Identification of FMR2, a novel gene associated with the FRAXE CCG repeat and CpG island

A large gene (FMR2) transcribed distally from the CpG island at FRAXE, and down-regulated by repeat expansion and methylation is identified, which is novel, expressed in adult brain and placenta, and shows similarity with another human protein, MLLT2, expressed from a gene at chromosome 4q21 involved in translocations found in acute lymphoblastic leukaemia cells.

A candidate gene for mild mental handicap at the FRAXE fragile site.

RT-PCR of normal adult brain RNA provides evidence for the existence of the 1495 bp transcript represented by the isolated cDNA, which possesses both a putative start of translation and a poly-A tail.

Structural and functional characterization of the human FMR1 promoter reveals similarities with the hnRNP-A2 promoter region.

The results from footprint studies suggest that the expression of the FMR1 gene is regulated by the binding of specific transcription factors to sequence elements in the 5' region of the gene and that this expression may be regulated by elements in common with the hnRNP-A2 gene.

Robust fragile X (CGG)n genotype classification using a methylation specific triple PCR assay

This syndrome is caused by mutations in the fragile X mental retardation-1 gene (FMR1), more than 95% of which involve hyperexpansion and hypermethylation of a polymorphic CGG trinucleotide repeat in the 59 untranslated region (59UTR) of the gene.



Isolation of sequences that span the fragile X and identification of a fragile X-related CpG island.

A single CpG island was identified in the cloned region between markers DXS463 and DXS465 that appears methylated in mentally retarded fragile X males, but not in nonexpressing male carriers of the mutation nor in normal males.

Isolation of the human chromosomal band Xq28 within somatic cell hybrids by fragile X site breakage.

These somatic cell hybrids, containing Xq27.3-qter as the sole human DNA, will aid the search for DNA associated with the fragile X site and will augment the high resolution genomic analysis of Xq28, including the identification of candidate genes for genetic-disease loci mapping to this region.

The fragile X site in somatic cell hybrids: an approach for molecular cloning of fragile sites.

By means of somatic cell hybrids containing either a normal human X or a fragile X chromosome and utilizing two genes that flank the fragile site as markers of chromosome integrity, segregation of these markers was shown to be more frequent if they encompass the fragile sites under appropriate culture conditions.

Strategy for molecular cloning of the fragile X site DNA.

The cloning approach employed to enhance the isolation of interspecific chromosome translocation junctions is described and it is suggested that the human portion of the translocation junction should be derived from the fragile X site sequence.

A rodent-human hybrid containing Xq24-qter translocated to a hamster chromosome expresses the Xq27 folate-sensitive fragile site.

A somatic cell hybrid containing a single human X chromosome bearing the Xq27 fragile site was lethally irradiated and re-hybridized to its HPRT- Chinese hamster parent. One of 24 colonies surviving

Abnormal pattern detected in fragile-X patients by pulsed-field gel electrophoresis

To detect rearrangements, or methylation changes that may reflect a locally inactive X chromosome, pulsed-field gel analysis of DNA from fragile-X patients with probes close to the fragile- X locus was used.

Fragile X genotype characterized by an unstable region of DNA

This probe provides a means with which to analyze fragile X pedigrees and is a diagnostic reagent for the fragile X genotype.

Four chromosomal breakpoints and four new probes mark out a 10-cM region encompassing the fragile-X locus (FRAXA).

The validation and use of a cell hybrid panel which allowed for a rapid physical localization of new DNA probes in the vicinity of the fragile-X locus (FRAXA) and three new polymorphic probes described here have a combined heterozygosity of 60% and represent a major improvement for genetic analysis of fragile- X families, in particular for diagnostic applications.

Implications of fragile X expression in normal males for the nature of the mutation

The hybrid system lowers the threshold for fragile X expression, a fragile site at Xq27 may be present on all human and chimpanzee X chromosomes and constitutes a previously unrecognized common fragile site and the hybrid system with caffeine post-treatment can distinguish between the common Xq 27 fragile sites of control males, the occult mutant fragile site of a transmitting male, and the fully expressed fragilesite of an affected male with XLMR.