This cross is designed to identify the genetic loci that control systolic and diastolic blood pressure in two intercrosses: C3H/HeJ X NZO/HILtJ (C3HxNZO) and NZOxC3H. There are 131 and 91 male F2 progeny from NZO lineage group and C3H lineage group, respectively. Total of 222 F2 mice with 92 genetic markers were used in the final QTL analysis (see note 1 in README file). Approximate coordinates for QTL analysis in centimorgans were obtained by dividing positions in megabases (Mb) by a factor of 2 (mouse genome build 33). The validity of this approximation was confirmed by comparison to estimated map positions in R/qtl. Systolic blood pressure (SBP) was strongly correlated with diastolic blood pressure (DBP) in the study population. Hence, we applied principal component analysis (PCA) to SBP and DBP to obtain the first principal component (PC1) that best explains the variation in blood pressure traits. QTL mapping for PC1 of blood pressure was performed using R/qtl. For detailed protocols see Nishihara et al 2007.