Genetic Polymorphisms of Three DNA-Repair Genes (PRKDC, XPD, XRCC1) are Related to Colorectal Cancer Susceptibility

XRCC1 R194W and R399Q Polymorphisms and Colorectal Cancer Risk in a Northeastern Mexican Population

Colorectal cancer (CRC) is one of the most common cancers worldwide. Its etiopathogenesis is complex, mainly influenced by genetic instability caused by the accumulation of mutations. The XRCC1 gene, which is involved in DNA repair, has been associated with CRC through the R194W (C194T) and R399Q (G399A) polymorphisms, but the results are inconsistent. Here, we analyzed the association of these polymorphisms with sporadic CRC in a northeastern Mexican population, including 155 male CRC patients and 155 male controls. Genotyping was performed using the RFLP method. An association with CRC was found for the 399A allele (G vs A; OR = 1.48 (1.03-2.13), P=0.034) and for the 399AA genotype in a codominant model (AA vs GG; OR = 3.11 (1.06-9.10), P=0.031). In contrast, there were no significant differences between CRC patients and controls for the C194T polymorphism (C vs T; OR = 0.82 (0.52-1.31), P=0.41). These results are consistent with many similar studies, but further research is needed to verify whether the XRCC1 R194W and R399Q polymorphisms play a role in CRC etiology. The functional significance of these polymorphisms is unclear, but some studies suggest that they influence DNA repair capacity and, thus, cancer risk.

Determination of Human Papillomavirus Type 18 Lineage of E6: A Population Study from Iran

The epidemiological studies in Iran on HPV18 nucleotide changes are rare. This type of virus is prevalent in the Iranian population. Therefore, in the present study, we aimed to identify the genetic variability in HPV18 in the E6 region to evaluate the prevalence of lineage distribution and sublineages in a sample population in Iran. Overall, 60 HPV18 confirmed cases were investigated between 2019 and 2021. The specimens were collected, and molecular genotyping was done using the Linear Array HPV Genotyping Test. DNA extraction was performed by a viral DNA/RNA kit. The HPV E6 gene was amplified by using type-specific primers designed according to the HPV18 genome prototype sequence. The sequencing of the E6 region was successfully done on 43 samples which were then compared to the reference sequence. The most frequent sublineage of HPV18 in this study was A4 (69.7%), followed by A1 (18.6%) and A3 (11.6%). Neither A2 nor A5 sublineage was not detected in this study. The related nucleotide acid changes according to the main references were as follows: A3: T104C/T232G/T485C/C549A, A4: T104C/T485C/C549A. The predominance of A lineage with the high frequency of A4 sublineage was found in the present research. The importance of sublineages in susceptibility to a progressive form of infection requires to be more investigated among the different population.