Association of Promoter Polymorphisms in Xrcc2 Gene Involved in DNA Double Strand Break Repair and Increased Susceptibility to Thyroid Cancer Risk in Pakistani Population

Thyroid cancer is the most prevalent endocrine malignancy with increasing incidence rate in recent years. Females are more likely to have thyroid cancer at a ratio of 3:1. The main risk factors of thyroid cancer are genetic factor, environmental factors and exposure to ionization radiations at childhood.

Exposure to ionization radiations cause single strand and double strand breaks and can produce chromosomal damage and release of reactive oxygen species that causes genomic instability. In human there are many pathways to repair this DNA damage, out of which double strand break repair (DSBR) pathway is an important and preferred pathway to repair such lesion.

This pathway has two types, non-homologous end joining (NHEJ) and homologous recombinant repair (HRR) pathway. HRR is an error prone pathway which is template specific and considered to play a significant role in the repair of DNA double strand damage produced by ionization radiations. HR encompasses many genes, but major role is performed by RAD51 and RAD51-like genes such as XRCC2 and XRCC3.

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