MAPPING OF 34 MINISATELLITE LOCI RESOLVED BY 2-DIMENSIONAL DNA TYPING

Two-dimensional (2-D) DNA typing is based on electrophoretic separatio n of genomic DNA fragments in two dimensions according to independent criteria (size and basepair sequence), followed by hybridization analy sis using multilocus probes. The technique allows simultaneous visuali zation of several hundred loci as spots in a 2-D pattern. The majority of the loci resolved are polymorphic. Using linkage analysis in a lar ge CEPH family, this study reports the mapping of 34 loci detected by the minisatellite core probe 33.6. By multipoint linkage analysis, reg ional chromosome positions of the 33.6 loci could be deduced, showing no evidence of clustering. In the analysis of spot patterns, use was m ade of a computerized image analysis system specifically designed for 2-D DNA typing. Since experimental variations between different separa tion patterns were automatically corrected for with this program, rapi d and reliable scorings could be obtained. The results presented demon strate the availability of reliable genetic information throughout the 2-D separation pattern. Adding the use of semiautomated computerized pattern analysis, this study further substantiates the applicability o f 2-D DNA typing in genome scanning, not only in theoretical but also in practical terms. Moreover, it can be anticipated that this method w ill have a specific advantage in studies that scan for trinucleotide r epeat expansions and somatic instability, where the repeat sequences d etected by appropriate core probes are of particular interest.