Mapping of DNA markers linked to the cystic fibrosis locus on the long arm of chromosome 7

We have used a panel of eight human/mouse somatic-cell hybrids, each containing various portions of human chromosome 7, and three patient cell lines with interstitial deletions on chromosome 7 for localization of six DNA markers linked to the cystic fibrosis locus. Our data suggest that D7S15 is located in the region 7cen→q22, that MET is located in 7q22→31, and that D7S8 and 7C22 are located in q22→q32. The hybridization results for COL1A2 and TCRB are consistent with their previous assignment to 7q21→q22 and 7q32, respectively. Given the location of these six markers and their linkage relationships, it is probable that the cystic fibrosis locus is in either the distal region of band q22 or the proximal region of q31. Using the same set of cell lines, we have also examined the location of another chromosome 7 marker PGY1. The data show that PGY1 is located in the region 7cen→q22, a position very different from its previous assignment.published_or_final_versio

Linkage of cystic fibrosis to the proα2(I) collagen gene, COL1A2, on chromosome 7

A linkage has been detected between the locus for cystic fibrosis (CF) and the proα2(I) collagen gene (COL1A2) which is located in the region q21.3→q22.1 of chromosome 7. Based on the combined linkage data derived from 50 informative two-generation nuclear families collected in Canada and Denmark, the distance between COL1A2 and CF is estimated to be 19 centiMorgans. Close lilnkage has also been detected between COL1A2 and the DNA market D7S15 (formerly D0CRI-917) and the serum enzyme activity marker paraoxonase (PON), both of which have previously been found linked to CF. The results of the two-oint and three-point linkage analyses indicate that the most probable order of these four genetic loci is COL1A2-D7S15-PON-CF.published_or_final_versio

Mapping of the cystic fibrosis locus on chromosome 7

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Physical localization of two DNA markers closely linked to the cystic fibrosis locus by pulsed-field gel electrophoresis.

Our previous linkage analysis suggested that the DNA segment D7S122 is located between MET and D7S8, the two genetic markers that are thought to flank the cystic fibrosis locus (CF). Subsequent chromosome walking experiments revealed that D7S122 in within close distance to another randomly isolated DNA marker, D7S340. To determine the physical relationship among D7S122, D7S340, MET, and D7S8, we have constructed a long-range restriction map of the region containing these four DNA segments, by using DNA from a human/hamster somatic hybrid cell line 4AF-KO15 (containing a single human chromosome 7) and a series of rare-cutting restriction enzymes. The combined results of complete, partial, and double digestion analyses confirm that D7S122 and D7S340 are located between MET and D7S8. The order of these markers is MET-D7S340-D7S122-D7S8, with distance intervals of approximately 500, 10, and 980 kbp, respectively. Together with family analysis, this information will be useful for eventual identification of the CF gene

Molecular approaches to the cystic fibrosis gene.

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Progress towards cloning the cystic fibrosis gene.

Genetic linkage analysis with polymorphic DNA markers (restriction fragment length polymorphisms: RFLPS) has allowed the assignment of the cystic fibrosis (CF) locus to the long arm of chromosome 7, within the region of band q31. Two of these markers, MET and D7S8, are tightly linked to the disease locus. Although recent data suggest that they are located on opposite sides of CF, the two can be separated by as much as 5 centimorgans. To obtain a better description of the CF locus and, eventually, to identify the affected gene, additional DNA markers are required to connect MET and D7S8, physically. We have screened the flow-sorted chromosome-7-specific library and thus far isolated 28 new probes from the 7q31 region by DNA hybridization analysis that uses a series of somatic cell hybrids containing various portions of human chromosome 7. Together with the previously identified markers, MET, D7S8, D7S13 and D7S16, these new markers should provide a fine genetic and physical map for the chromosomal region surrounding CF. DNA segments can then be sequentially cloned by chromosome walking from points closest to the CF locus and examined for genes that are preferentially expressed in tissues known to be affected in the disease.link_to_subscribed_fulltex

Microdissection and microcloning of the long arm of human chromosome 7

DNA-fragments from the region of the long arm of human chromosme 7 to which the CF-locus has been mapped recently were isolated by microdissection and microcloning. We developed a new fixation procedure resulting in inserts of 1.0-7.0 kb in length with a mean value of 2.9 kb. Regional mapping of three clones on 7q was carried out by the use of different hybrid cell lines containing fragments of human chromosome 7. © 1987 Martinus Nijhoff Publishers.link_to_subscribed_fulltex