GENOMICS 11, 737-743 (1991) A Somatic Cell Hybrid Panel and DNA Probes for Physical Mapping of Human Chromosome 7p A. VORTKAMP, * U. THIAS, * M. GESSLER, * W. ROSENKRANZ, t P. M. KROISEL, t N. TOMMERUP,*' 1 G. KRÜGER,§ J. GÖTZ,§ l. PELZ,§ AND K.-H. GRZESCHIK* *Institut far Humangenetik der UniversitCit, Bahnhofstrasse 7, D-3550 Marburg, Federal Republic of Germany; t Institut far Medizinische Biologie und Humangenetik der UniversitCit, Harrachgasse 21/8, A-80 10 Graz, Austria; §Kinderk/inik der Universit3t, Rembrandtstrasse 16/17, 0-2500 Rostock, Federa/ Republic of Germany; and *1. F. Kennedy Institute, G. I. Landevej 7, DK-2600 Glostrup, Denmark Received May 8, 1991 ; revised July 12, 1991 To identify by reverse 1enetics genes on the short arm of human chromosome 7 to involved b:a the regula- tion of human craniofacial and limb development, we have set up a human mouse somatic cell hybrid panel that divides 7p into 9 fragments. The breakpoints are defined by dele- tions or translocations involving one chromosome 7 in the cells of the human cell fusion partners. Particularly densely covered with these cytogenetic anchor points is the proximal area of 7p within and around 7p13. The number of cytogenetic mapping points within proximal 7p could be increased by four, using two diploid human celllines with small interstitial deletions in this region for dosage studies. We used Southern blots oftbis panel to assign to 7q or subre- gions of 7p more than 300 arbitrary DNA probes or genes that provide reference points for physical mapping of 7p. Three reciprocal translocations with one of the break- points in 7pl3 mark tbe location of a gene involved in Greig cephalopolysyndactyly syndrome. To deftne an area in wbich we could identify candidatel fortbis developmen- tal gene, we established a macrorestriction map using probe& ftanking the putative gene region. The Greig trans- locations were found tobe located within a 630-kb Notl restriction fragment. c 1991 Acaclemlc Pl'eii,Inc. INTRODUCriON Detailed physical and genetic maps are one prereq- uisite for the search for particular human genetic dis- ease loci by reverse genetics. Unless microscopically visible mutations guide the way to the gene as was the case in DMD (Boyd et al., 1986), several open reading frames in a chromosome region identified by linkage studies must be considered as candidate genes and 1 Present address: Department of Medical Genetics, Ullevaal Hospital, P.B. 1036 Blindem, 0315 Oslo, Norway. 737 analyzed individually (Estivill et al., 1987; Rommens et al., 1989). It has been suggested that the short arm of human chromosome 7 carries a gene cluster involved in cra- niofacial and limb development (Brueton et al., 1988; Winter and Huson, 1988; Pohl et al., 1990). Particu- larly rewarding for a reverse genetics search in this area is the gene underlying the G:reig cephalopolysyn- dactyly syndrome (GCPS) because cytogenetic pecu- liarities, two translocations and three deletions, af- fecting band 7p13 have been associated with this syn- drome (Tommerup and Nielsen, 1983; Krüger et aL, 1989; Wagner et al., 1990; Pettigrew et al., 1989). We bad previously used cells from a Greig patient with a third translocation, t(6;7), involving a breakpoint in 7p13 for gene mapping with somatic cell hybrids (Jo- hannsmann et al., 1980). The syndrome consists of polydactyly of the hands, pre- and postaxial polysyndactyly of the feet, macrocephaly, prominent forehead, broad nasal bridge, and hypertelorism (Greig, 1926). Inheritance is autosomal dominant with complete penetrance but considerable intrafa- milial variability (Temtamy and McKusick, 1969). A mouse model for the Greig syndrome may exist in the mutant extra-toes (Xt) (Johnson, 1967) and the prob- ably allelic mutation anterior digit-pattern deformity (add) that has recently been described (Pohl et al., 1990). In addition to a complex abnormality of embry- onie development, a fundamental disturbance of the process of ossification may be associated with GCPS (Brueton et al., 1988). Tommerup and Nielsen (1983) postulated a role of the gene(s) involved in this syn- dromein neoplasia on the basis of the similarity of certain abnormalities to those that occur in the heredi- tary basal cell carcinoma syndrome. Dominant mutations of a gene disturbing pattem formation in human and mouse and possibly predis- posing to certain malignancies are of considerable gen- 0888-7543/91 $3.00 Copyright @ 1991 by Academic Press, Inc. All rights of reproduction in any form reserved.