Firstly, the gene for ACE2 maps to a defined quantitative trait locus on the X chromosome, previously identified as a quantitative locus for blood pressure (Crackower et al., 2002), in three strains of genetically hypertensive rats the Sabra salt-sensitive rat, spontaneously hypertensive rat (SHR) and the stroke-prone SHR. The gene discussed is ACE2; the disease is stroke disorder.