Substitution mapping of a blood pressure quantitative trait locus to a 2.73 Mb region on rat chromosome 1

Objective To improve the localization of a blood pressure quantitative trait locus (BP QTL) on rat chromosome (RNO) 1. Methods Congenic substrains were derived from the progenitor congenic strains S.LEW(D1 Mco4X1) and S.LEW(D1 Mco4X5) which previously localized a BP QTL (region 2) to a developed congenic substrains, along with control Dahl salt-sensitive (S) rats were fed a 2% NaCl diet for 24 days before their BP was compared by both tail-cuff and radiotelemetry methods. Results By comparing BP of these congenic substrains to that of S rats, we have refined the location of the BP QTL2 region to a 2.73 Mb genomic interval that contains 19 annotated genes in the latest rat genome assembly (version 2.1). Slc9a3, the gene encoding the Na+/H+ exchanger 3, originally a candidate gene in the BP QTL2 region, is excluded based on its map location. Conclusion Substitution mapping was used to reduce a BP QTL on RNO1 from 17 centimorgans (cM) to similar to1.4 cM (= 2.73 Mb). This region now contains 19 annotated rat candidate genes. (C) 2003 Lippincott Williams Wilkins.