Human Thymine DNA glycosylase or hTDG was first discovered in 1993 in Josef Jiricnyâ€™s laboratory from HeLa cells extract . Thymine DNA glycosylase was named because of its ability to excise T from GÂ·T mispair which predominantly arise due to spontaneous deamination of 5-methyl cytosine at CpG sites in mammals by AID/APOBEC enzyme . Initially TDG attracted attention due to its DNA repair activity initiating Base Excision Repair (BER) pathway. Participating in BER TDG protect our genome from hazardous mutation. Subsequent research on TDG opens up many new insights of TDGâ€™s structure, function and mechanism. Few recent discoveries like, TDG is essential for embryonic development, interacts with many transcription factors and regulates gene expression and its important role in active DNA demethylation brought TDG in limelight of research especially in the field of epigenetic. Thus in mammal TDG is an essential enzyme with multifunctional activity.