Single nucleotide polymorphisms and risk factors predictive of pancreatic adenocarcinoma

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease progressing asymptomatically until death within months after diagnosis. Defining at-risk populations should promote an early diagnosis and efficient follow-up, therefore avoiding its development. Single nucleotide polymorphisms, or SNPs, constitute the most abundant form of genetic variation in the human genome. SNPs are markers of diverse populations or individuals, yet also can be associated with differences in susceptibility or severity of certain diseases and/or individual responses to drugs. Many SNPs have previously been identified in studies of healthy subjects and patients with different alleles of a given gene. To date, around forty SNPs from the human genome have been correlated with predisposition to PDAC by pan-genomic studies or genome wide association studies (GWAS). However, parts of the human genome located within the GC-rich repeated domain of chromosomes are unsuitable for GWAS. Unfortunately, of those forty SNPs none are currently used in routine clinical protocols as potential biomarkers for PDAC. Exon 11 of the bile salt-dependent lipase gene ( BSDL ) plays a key role in pancreatic disease and encodes variable number of tandem repeat (VNTR) sequences, therefore Martinez et al . [Oncotarget. 2015; 6: 39855-39864.] hypothesized that a genetic link exists between mutations in VNTR loci and predisposition to pancreatic cancer (PC). Authors reported that the c.1719C>T transition (SNP rs488087) present in BSDL VNTR may be a useful marker for defining a population at risk of developing PC (occurrence: 63.90% in the PC group versus 27.30% in the control group). Notably, the odds ratio (OR) of 4.7 for the T allele was larger than those already determined for other SNPs suspected to be predictive of PC. Further studies on tumor pancreatic tissue suggested that the T allele may favor Kras G12R/G12D somatic mutations which represent negative prognostic factors associated with reduced survival. Furthermore, a robust method using probes for droplet digital (dd)-PCR was designed to specifically discriminate the C/C major from C/T or T/T minor genotypes. Altogether, Martinez et al . propose that detection of the T allele in rs488087 SNP should lead to an in-depth follow-up of these patients, particularly if associated with other potential risk factors of PC.