Chetsanga has discovered two enzymes involved in the repair of damaged DNA: firstly, formamidopyrimidine DNA glycosylase, which removes damaged 7-methylguanine from DNA (1979),  and secondly, purine imidazole-ring cyclase, which re-closes imidazole rings of guanine and adenine damaged by x-irradiation (1985).
According to Chetsanga, his research focus in his scientific career has been on DNA and RNA structural and functional details as they relate to cellular metabolism and disease development.