PKD1 and polycystic kidney disease: At least 2 genetic loci have been identified as important determinants; PKD1 (chromosome 16p13.3) and 2 (chromosome 4q21), which encode polycystin 1 (European Polycystic Kidney Disease Consortium 1994) and 2 (Silvia González-Perrett et al. 2001) respectively.