Journal of Human Genetics, an intense genetic analysis of this disorder was carried out. The genetic mapping effort culminated in the multipoint linkage map shown in Fig. 2, which was constructed by David Goldgar and colleagues from the collaborative group's eflbrtsS. This multipoint map represents the outcome of the study of 142 families with over 700 affected individuals, and a total of 13 838 genotypings. It is apparent from Fig. 2 that probes on either side of NF1 are now available within less than 5 cM of the gene, so that application of DNA technology to prenatal or presymptomatic diagnosis of this disease is now possible. This genetic analysis thus places NF1 on the proximal long arm of chromosome 17. Initial surveys of this region revealed at least three candidate genes: two of these, the nerve growth factor receptor and the erbA1 proto-oncogene, were quickly shown to map distal to NF1 by the identification of recombinant individuals< 9: a third candidate gene, the erbB2 proto-oncogene (also sometimes called NE6'I HER2 or NGL), has not yet yielded a polymorphism and so could not be mapped genetically. Subsequent physical mapping experiments, however, have now also excluded this locus (see bek) w).