Telomerase is an RNA-dependant DNA polymerase that catalyzes the addition of telemoric repeat, TTAGGG to chromosome ends. Telomerase is composed of an internal telomerase RNA template (TERC) and the enzyme, telomerase reverse transcriptase (TERT or TP2). Telomerase expression is usually repressed in postnatal somatic cells resulting in shortening of telomeres. Overexpression of telomerase may be implicated with oncogenesis.