Distribution of Ha-RAS-1 proto-oncogene alleles in breast cancer patients and in a control population.

The frequencies of 13 different Ha-ras proto-oncogene alleles have been estimated in 92 breast cancer patients and 60 unaffected individuals. The Ha-ras alleles can be identified using a DNA restriction fragment length polymorphism (RFLP) closely linked to the 3' end of the gene, and are characterized by a different length due to a region of sequences repeated a variable number of times (variable tandem repeats, VTR). The statistical analysis of the data obtained shows that the frequency of alleles ranging between specific length limits is significantly higher in breast cancer patients than in controls. The same applies to specific genotypes bearing the aforementioned alleles. This suggests that the inheritance of these alleles may be associated with an increased risk of developing breast cancer.