Genetic predisposition to human lung cancer.

The influence of polymorphic variants of the human c-Ha-ras gene on predisposition to lung cancer has been investigated. The human c-Ha-ras gene has been shown to reside on a polymorphic BamH1 restriction fragment. This restriction fragment length polymorphism (RFLP) results from variation in the size of a region of repetitive DNA 3' to the gene. An attempt has been made to characterise and compare the c-Ha-ras RFLP's in a normal population and in a group of cancer patients. DNA was extracted from the white blood cells of 101 normal donors and four common Ha-ras alleles identified, with occasional rare alleles of various sizes. The allele frequencies were examined in 132 lung cancer patients, comprising 66 individuals with small cell carcinoma of the lung (SCCL) and 66 with non-small cell carcinoma of the lung (non-SCCL). An abnormal allele distribution was found in individuals with non-SCCL compared to both control and SCCL values suggesting a degree of genetic pre-position to non-SCCL. In addition, analysis of the Ha-ras RFLP's in solid samples inferred a deletion of material from the short arm of chromosome 11 in two of 16 informative samples.