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Biomedical subjects

Sharon Marsh

Publications and source records attributed to Sharon Marsh.

38 records · Page 3Linked to original sources

SNP databases and pharmacogenetics: great start, but a long way to go.

With the recent publication of the human genome project there has been an explosion of data available for pharmacogenetic research. Web-based databases containing information on single nucleotide polymorphisms (SNPs) are readily accessible to researchers, but there has been little comment on their utility. We used seven major international databases to identify SNPs in 74 genes involved in drug pathways. Very little overlap was seen among the databases, with only eight out of a putative 893 SNPs ( approximately 1%) common to the most commonly used databases. Problems with false positives, secondary to a high degree of homology in gene families, were also observed. These studies suggest researchers limiting their studies to one database would miss a great deal of information. Effort to update compilation databases, such as HGVbase, GeneSNP, PharmGKB, and HOWDY, and the aggressive removal of false positives from all databases is required if these resources are to facilitate the intended growth in pharmacogenetics research.

Amino Acid Sequence↗

Primary colorectal tumour is not an accurate predictor of thymidylate synthase in lymph node metastasis.

Analysis of tumour markers is helping to predict individual patient response to chemotherapy. However, the difficulties in obtaining metastatic disease samples has led to a reliance on assessment of primary tumour, with little data on its predictive ability. This study assessed thymidylate synthase (TS), a target for the commonly used drug 5FU, in 42 paired primary colorectal tumour and lymph node metastasis. High TS staining was seen in 63% of primary colon tumour cells and 81% of the secondary lymph node. Primary tumour did not have significant predictive power for secondary tumour samples (kappa=0.125; p=0.38). There was no significant relationship between TS staining and expression of G1/S cell cycle proteins p21, p27, p53, cyclin D1, proliferating cell nuclear antigen (PCNA) and retinoblastoma protein (Rb) (p>0.05 in all cases). Discordance in TS protein levels between primary and secondary tumours demonstrates the danger of predicting outcome after chemotherapy in metastatic colorectal cancer from the primary tumour.

Adult↗