摘要：A variable tandem repeat (VTR) is responsible for the hyperallelism one kilobase 3' to the human c-Ha-ras-1 (Ha-ras) gene. Thirty-two distinct restriction fragments, comprising 3 allelic classes by frequency of occurrence, have thus far been detected in a sample size of approximately 800 caucasians. Rare Ha-ras alleles, 21 in all, are almost exclusively confined to the genomes of cancer patients (p less than 0.001). From our data we have computed the relative cancer risk associated with possession of a rare Ha-ras allele to be 27. To understand the molecular basis for this phenomenon, we have begun to clone Ha-ras fragments from nontumor DNA of cancer patients. We report here the weak activation, as detected by transfection and transformation of NIH 3T3 mouse cells, of two Ha-ras genes which were obtained from lymphocyte DNA of a melanoma patient. We have mapped the regions that confer this transforming activity to the fragment containing the VTR in one Ha-ras clone and the fragment containing gene coding sequences in the other. Full text Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (1.8M), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References . 147 148 149 150 151 152 153
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