DNA damage/lesions caused by oxidizing/alkylating exogenous agents (ionizing radiation, pesticides, and chemotherapeutic agents) and endogenous agents (metabolites, oxidative phosphorylation, and free radicals) are implicated in several human pathologies including cancer and neurodegenerative diseases. BER-pathway is the primary repair system against these DNA lesions. Two types of BER sub-pathways exists; short-patch and long-patch BER takes place in mammalian cells depending upon the type of damage, concentration of the participant BER protein(s) and thus, finally allowing the replacement of the damaged DNA gap by single nucleotide and multi-nucleotides respectively. DNA damage/lesions caused by oxidizing/alkylating exogenous agents (ionizing radiation, pesticides, and chemotherapeutic agents) and endogenous agents (metabolites, oxidative phosphorylation, and free radicals) are implicated in several human pathologies including cancer and neurodegenerative diseases. BER-pathway is the primary repair system against these DNA lesions. Two types of BER sub-pathways exists; short-patch and long-patch BER takes place in mammalian cells depending upon the type of damage, concentration of the participant BER protein(s) and thus, finally allowing the replacement of the damaged DNA gap by single nucleotide and multi-nucleotides respectively