S1811 Pancreatitis Susceptibility in Hyperparathyroidism: Evidence for a Complex Genetic Trait Including SPINK1, CFTR, CTRC and PRSS2 Mutations

Abstract

expression profiling using scant specimens obtained via endoscopic ultrasound guided fine needle aspiration (EUS-FNA) and to describe a new method of direct gene sequencing, which has a number of advantages over conventional cDNA microarrays. Methods: We enrolled patients with pancreatic masses in whom cancer was suspected who presented for EUS. During FNA of the mass, one extra pass of a 22-g needle was used to obtain tissue for the study. Total RNA was extracted from each sample and analyzed by Solexa highthroughput RNA sequencing (RNA-Seq), which provides an unbiased genome-wide analysis of the transcriptome. The underpinning of RNA-Seq is that 36 base pair nucleotide sequences can be uniquely mapped to the genome thus enabling the unbiased digital quantification of a tissue's complete cDNA population. Moreover, unlike conventional cDNA microarray analysis of limited tissue samples, RNA amplification is not required using the RNA-Seq method. Results: 14 patients have been enrolled so far. One case was excluded because of the absence of epithelial cells in the EUS-guided FNA. Total yield of RNA per sample ranged from 4-18 micrograms (ug), with a mean of 9 ug/sample). Six samples have undergone RNA-Seq. Preliminary analyses show that RNA-Seq libraries have 2-3 million uniquely mapped sequence reads that cluster into ~14,000 known gene exons and also identify ~5,000 novel transcripts or exons (Storey Q < 0.05). Comparative expression profiling between cases of ductal adenocarcinoma and benign pancreatitis is currently in progress. Conclusion: EUS-guided FNA yields sufficient tissue for RNA extraction and RNA-Seq expression profiling without RNA amplification. The ability to use specimens obtained via EUS will greatly expand the availability of tissue for this type of research since most patients with pancreatic cancer do not undergo surgical resection but do have biopsies. Direct RNA-Seq is a promising new method for genome-wide expression analysis and may in time lead to the discovery of novel molecular targets in pancreatic cancer screening and/or therapy.