Tumor Suppressor Genes

Tumor suppressor genes or anti-oncogenes generally inhibit cell division in cooperation with proto-oncogenes. The very existence of these genes prevents cells from undergoing neoplastic transformation. While tumor suppressor genes are inactivated by mutations or are deleted, the absence of their protein products permits malignant growth to occur. The most extensively studied disease caused through suppressor genes is the childhood tumor retinoblastoma (cancer of the retina). The gene included is Rb and the genotype of normal individuals is Rb/Rb. A prerequisite of tumor creation is the development of homozygosity or heterozygosity of the rb allele. The possible genetypes for retinoblastoma are, hence, rb/rb; rb/- or -/-