Background: In Down syndrome, the incidence of solid tumors including lung cancer is considerably lower than that of the general population. The low risk of lung cancer in individuals with Down syndrome may be related to the gene-dosage effect of the extra chromosome 21. It may suggest that tumor suppressor genes playing a role in the pathogenesis of lung cancer may be present on chromosome 21.
Methods: A total of 39 surgically resected non-small cell lung cancers were analyzed using nine microsatellite markers for 21q. Loss of heterozygosity was considered to be present when the signal intensity of the allele in tumor DNA was less than 50% of that in the corresponding normal DNA.
Results: Loss of heterozygosity for at least one locus was detected in 22 of 39 tumors (56.4%). Allelic loss was frequently detected at three distinct regions: at the locus D21S1432 on 21q21.1, the region between D21S1435 and D21S1442 on 21q21.2 to 21.3, and the region between D21S1270 and D21S1445 on 21q22.1.
Conclusions: These results indicate that loss of heterozygosity on 21q may play an important role in the pathogenesis of non-small cell lung cancer.