SPINK1 and PRSS1 mutations in benign pancreatic hyperenzymemia.

UNLABELLED: The aim of this study was to determine whether mutations in SPINK1/PRSS1 genes are associated with benign pancreatic hyperenzymemia (BPH). METHODS: Sixty-eight subjects with BPH (including 13 familial cases) were studied. In all, we sequenced germline DNA for all the exons and intro-exon boundaries of PRSS1 and SPINK1. RESULTS: Nine (13.2%) of the 68 subjects harbored PRSS1 or SPINK1 mutations. As to PRSS1, no hereditary pancreatitis-associated variant was detected, whereas previously undescribed mutations (p.Ala148Val and c.40+1G>A) were respectively found in 2 subjects (2.9%). SPINK1 mutations were detected in 7 subjects (10.3%). Five of them exhibited known mutations (3 p.Asn34Ser, 1 p.Pro55Ser, and 1 c.88-23A>T), whereas 2 had a newly found variant (p.Arg67Gly and c.*32C>T, respectively). Only 2 familial BPH, belonging to 2 different families, were found to carry a mutation (1 with p.Ala148Val for PRSS1 and 1 with p.Asn34Ser for SPINK1). CONCLUSIONS: No known mutations of PRSS1 have been found in BPH, whereas the frequency of known SPINK1 variants is similar to that reported in the general population. No segregation of PRSS1/SPINK1 variants occurs in BPH families. Benign pancreatic hyperenzymemia cannot be explained by mutations in genes whose variants are known to be associated with pancreatitis or by mutations in other PRSS1/SPINK1 genes.

Constraints imposed by supercoiling on in vitro amplification of polyomavirus DNA.

Previous attempts to identify oncogenic polyomaviruses in human cancers have yielded conflicting results, even with the application of PCR technology. Here, it was considered whether the topological features of the polyomavirus genome interfere with efficient PCR amplification. Plasmid and SV40 DNAs were used as a model system for comparing the amplification efficiency of supercoiled, circular relaxed and linear templates. It was found that detection of circular templates required 10 times more molecules than detection of identical but linear templates. Supercoiling hindered the in vitro amplification of SV40 circles by a factor of 10, and erratic amplification of supercoiled SV40 occurred with subpicogram amounts of template. Accordingly, topoisomerase I treatment of DNA improved the PCR detection of supercoiled SV40, significantly decreasing the number of false-negative samples. Previously described, yet controversial, polyomavirus presence in human tissues should be reconsidered and topoisomerase I-sensitive polyomavirus amplification might help to detect polyomavirus genomes in mammalian tissues.