Frequencies of TP53 Germline Variations and Identification of Two Novel 3’UTR Variants in a Series of Head and Neck Cancer Cases

Abstract

AbstractTP53 is a tumour suppressor gene. Its inactivation plays a significant role in the molecular pathology of cancers. TP53 germline mutations increase the risk of developing multiple primary cancers. However, the role of alterations in TP53 germline DNA in head and neck cancers (HNCs) is not well-established. HNCs comprise one of the most frequent cancers in South Asia. The present discovery study reports the investigation of germline variations in the TP53 gene in a cohort of 30 HNC patients from Karachi, Pakistan. Blood samples were collected and genomic DNA was extracted from white blood cells. TP53 has 11 exons, where exon 1 is not transcribed. After quality control of DNA, amplification of seven selected exons along with their splice sites, two intronic regions (introns 2-3 and 3-4), and 3’UTR were carried out. Sanger sequencing was carried out in order to identify germline variations. Comparison with wild type sequence revealed rs1642785 G>C (intron 2-3) variation in 63.2%, PIN3 duplication (rs17878362) in intron 3-4 in 94.7%, and rs1042522 G>C in exon 4 (p.R72P) in 66.6% of the cases. In 3’UTR, 13.4% of the analyzed cases carried either one of two variants, i.e., 17:7669567_8delCA or 17:7669560C>G. The latter variations are reported for the first time in literature. In conclusion, we report three highly frequent germline variations and two newly discovered variations in 3’UTR of TP53 germline DNA in HNC patients from Pakistan. These results shall contribute to delineating the genetic component of HNCs with potential translational implications.