Biomaterial Database

The fragile X site in somatic cell hybrids: an approach for molecular cloning of fragile sites. 1987

S T Warren, and F Zhang, and G R Licameli, and J F Peters

Fragile X syndrome is a common form of mental retardation associated with a fragile site on the human X chromosome. Although fragility at this site is usually evident as a nonstaining chromatid gap, it remains unclear whether or not actual chromosomal breakage occurs. 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 site under appropriate culture conditions. Hybrid cells that reveal marker segregation were found to contain rearranged X chromosomes involving the region at or near the fragile site, thus demonstrating true chromosomal breakage within this area. Two independent translocation chromosomes were identified involving a rodent chromosome joined to the human X at the location of the fragile site. DNA analysis of closely linked, flanking loci was consistent with the position of the breakpoint being at or very near the fragile X site. Fragility at the translocation junctions was observed in both hybrids, but at significantly lower frequencies than that seen in the intact X of the parental hybrid. This observation suggests that the human portion of the junctional DNA may contain part of a repeated fragility sequence. Since the translocation junctions join heterologous DNA, the molecular cloning of the fragile X sequence should now be possible.

UI	MeSH Term	Description	Entries
D007041	Hypoxanthine Phosphoribosyltransferase	An enzyme that catalyzes the conversion of 5-phosphoribosyl-1-pyrophosphate and hypoxanthine, guanine, or MERCAPTOPURINE to the corresponding 5'-mononucleotides and pyrophosphate. The enzyme is important in purine biosynthesis as well as central nervous system functions. Complete lack of enzyme activity is associated with the LESCH-NYHAN SYNDROME, while partial deficiency results in overproduction of uric acid. EC 2.4.2.8.	Guanine Phosphoribosyltransferase,HPRT,Hypoxanthine-Guanine Phosphoribosyltransferase,IMP Pyrophosphorylase,HGPRT,HPRTase,Hypoxanthine Guanine Phosphoribosyltransferase,Phosphoribosyltransferase, Guanine,Phosphoribosyltransferase, Hypoxanthine,Phosphoribosyltransferase, Hypoxanthine-Guanine,Pyrophosphorylase, IMP
D008297	Male		Males
D002460	Cell Line	Established cell cultures that have the potential to propagate indefinitely.	Cell Lines,Line, Cell,Lines, Cell
D002871	Chromosome Banding	Staining of bands, or chromosome segments, allowing the precise identification of individual chromosomes or parts of chromosomes. Applications include the determination of chromosome rearrangements in malformation syndromes and cancer, the chemistry of chromosome segments, chromosome changes during evolution, and, in conjunction with cell hybridization studies, chromosome mapping.	Banding, Chromosome,Bandings, Chromosome,Chromosome Bandings
D003001	Cloning, Molecular	The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.	Molecular Cloning
D005260	Female		Females
D005600	Fragile X Syndrome	A condition characterized genotypically by mutation of the distal end of the long arm of the X chromosome (at gene loci FRAXA or FRAXE) and phenotypically by cognitive impairment, hyperactivity, SEIZURES, language delay, and enlargement of the ears, head, and testes. INTELLECTUAL DISABILITY occurs in nearly all males and roughly 50% of females with the full mutation of FRAXA. (From Menkes, Textbook of Child Neurology, 5th ed, p226)	FRAXA Syndrome,FRAXE Syndrome,Martin-Bell Syndrome,Fra(X) Syndrome,Fragile X Mental Retardation Syndrome,Fragile X-F Mental Retardation Syndrome,Mar (X) Syndrome,Marker X Syndrome,Mental Retardation, X-Linked, Associated With Fragile Site Fraxe,Mental Retardation, X-Linked, Associated With Marxq28,X-Linked Mental Retardation and Macroorchidism,FRAXA Syndromes,FRAXE Syndromes,Fragile X Syndromes,Marker X Syndromes,Martin Bell Syndrome,Syndrome, FRAXA,Syndrome, FRAXE,Syndrome, Fragile X,Syndrome, Marker X,Syndrome, Martin-Bell,Syndromes, FRAXA,Syndromes, FRAXE,Syndromes, Fragile X,Syndromes, Marker X,X Linked Mental Retardation and Macroorchidism
D005954	Glucosephosphate Dehydrogenase		Glucose-6-Phosphate Dehydrogenase,Dehydrogenase, Glucose-6-Phosphate,Dehydrogenase, Glucosephosphate,Glucose 6 Phosphate Dehydrogenase
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D006822	Hybrid Cells	Any cell, other than a ZYGOTE, that contains elements (such as NUCLEI and CYTOPLASM) from two or more different cells, usually produced by artificial CELL FUSION.	Somatic Cell Hybrids,Cell Hybrid, Somatic,Cell Hybrids, Somatic,Cell, Hybrid,Cells, Hybrid,Hybrid Cell,Hybrid, Somatic Cell,Hybrids, Somatic Cell,Somatic Cell Hybrid