title: Fragile X genotype characterized by an unstable region of DNA.
abstract: DNA sequences have been located at the fragile X site by in situ hybridization and by the mapping of breakpoints in two somatic cell hybrids that were constructed to break at the fragile site. These hybrids were found to have breakpoints in a common 5-kilobase Eco RI restriction fragment. When this fragment was used as a probe on the chromosomal DNA of normal and fragile X genotype individuals, alterations in the mobility of the sequences detected by the probe were found only in fragile X genotype DNA. These sequences were of an increased size in all fragile X individuals and varied within families, indicating that the region was unstable. This probe provides a means with which to analyze fragile X pedigrees and is a diagnostic reagent for the fragile X genotype.
authors.affiliation: Department of Cytogenetics and Molecular Genetics, Adelaide Children's Hospital, South Australia.
authors.forename: S
authors.initials: S
authors.lastname: Yu
authors.forename: M
authors.initials: M
authors.lastname: Pritchard
authors.forename: E
authors.initials: E
authors.lastname: Kremer
authors.forename: M
authors.initials: M
authors.lastname: Lynch
authors.forename: J
authors.initials: J
authors.lastname: Nancarrow
authors.forename: E
authors.initials: E
authors.lastname: Baker
authors.forename: K
authors.initials: K
authors.lastname: Holman
authors.forename: J C
authors.initials: JC
authors.lastname: Mulley
authors.forename: S T
authors.initials: ST
authors.lastname: Warren
authors.forename: D
authors.initials: D
authors.lastname: Schlessinger
mesh_terms: D002874:Chromosome Mapping; D004247:DNA / Q000235:genetics*; D005260:Female; D005600:Fragile X Syndrome / Q000235:genetics*; D005838:Genotype; D006801:Humans; D006822:Hybrid Cells / Q000166:cytology; D008297:Male; D009693:Nucleic Acid Hybridization; D012016:Reference Values; D015183:Restriction Mapping; D014960:X Chromosome
chemical_list: D004247:DNA