10TH ANNIVERSARY ARTICLE Physical Mapping of the Human Chromosome 11q23 Region Containing the Ataxia- Telangiectasia Locus Shan Wei, Mariano Rocchi, Nicoletta Archidiacono, Nicoletta Sacchi, Giovanni Romeo, and Richard A. Gatti ABSTRACT: Two breakpoints within chromosome 11q23 were characterized with 29 DNA probes to establish a physical map of the region. This region is notable in that it contains at least 14 functional genes which are also syntenic in the mouse (chromosome 9). Chromosome 11q23 includes these markers: STMY, CLG, NCAM, DRD2, APOA1, APOC3, APOA4, CD3E, CD3D, CD3G, PBGD, THY1, ets-1, and cbl-2. The two breakpoints, herein called "X;11" and "4;11," defined a region of approximately 8 cM containing the APO and CD3 complexes as well as the polymorphic marker DllS29. DRD2 localized centromeric to the X;11 breakpoint despite evidence for close genetic linkage to DllS29, suggesting that DRD2 lies close to the X;11 breakpoint. THY1, PBGD, and cbl-2 localized telomeric to the 4;11 breakpoint and thus to the [1911S29--APO--CD3] grouping as well. The physical map helps to correlate the cytogenetic and linkage maps of this region. It also suggests that the human 1 lq23 syntenic grouping is inverted with respect to its murine counterpart. Based on this physical map and on our primary linkage map of the 1 lq23 region, we are able to confirm a preliminary localization of the gene for ataxia- telangiectasia group A (ATA) to a region centromeric to the interval defined by DllS144 (pYNB3.12) and THY1. INTRODUCTION We recently localized a gene for ataxia-telangiectasia group A [ATA] to chromosome 11q22-23 by linkage analyses using two genetic markers, THY1 and pYNB3.12 [1]. DNA from a large Amish pedigree was used to screen 171 markers, or approximately 35% of the genome, before this linkage was found. The most likely order of the three loci placed ATA outside of THY1 and pYNB3.12, closer to pYNB3.12 (pYNB3.12 is hereafter termed DllS144. It is also termed MCT128.1, DllS148 and DllS285 in the literature.) Additional polymorphic markers in this region have since been tested. However, we cannot calculate location scores for ATA until the proper order and distances between those markers have been established. We define herein whether various markers on distal 11q localize centromeric From the Department of Pathology, University of California at Los Angeles (S. W., R. A. G.), Los Angeles. California, Department of Human Genetics, Gaslini Institute, Genoa (M. R., N. A., G. R.), Italy, and the National Cancer Institute (N. S.), Frederick, Maryland. Address reprint requests to: Dr. R. A. Gatti, M.D., UCLA School of Medicine, Department of Pathology, Los Angeles, CA 90024. Received July 13, 1989; accepted August 10, 1989. 1 © 1990 Elsevier Science Publishing Co., Inc. Cancer Genet Cytogenet 46:1-8 (1990} 655 Avenue of the Americas, New York, NY 10010 0165-4608/90/$03.50