Identification of genetic polymorphisms in the 'expressed sequence tag' (EST) database

Abstract

▼Genetic variation in the human population has beenstudied to gain insight into the functional importance ofspecific genes in disease and drug metabolism. For ex-ample, polymorphic variants of genes that are importantin the regulation of blood pressure, blood clotting andblood lipids are studied in relation to cardiovascular dis-ease (Ref. 1). The relation of detoxification enzymes to can-cer risk (Ref. 2, 3, 4, 5, 6, 7) and idiosyncratic drug effects(Ref. 8, 9), the latter with the aim to obtain individual-ized drug-therapy regimens, are the focus of world-wide ef-forts. Individual genotyping can now be performed quicklyand easily by PCR-based methods utilizing minute quan-tities of DNA. However, finding new unknown polymor-phisms in a gene is a tedious task involving either a searchfor restriction fragment length polymorphisms (RFLPs) onSouthern blots or PCR amplifications of suitably sized seg-mentsofthegene,followedbysingle-strand-conformation-polymorphism (SSCP) analysis or direct DNA-sequence de-termination. Because of the considerable interest in, andplans of, cataloguing human DNA sequence variation (Ref.10), improved methodology, including minisequencingstrategies, multiplex reverse dot blots, DNA chips and aTaqMan approach is being developed. However, we showhere that a considerable amount of human DNA sequencevariants can be found