 The HapMap initially only looked for common variants (SNPs include by definition only common variants). This was in line with the so-called common disease/common variant (CD/CV) hypothesis formulated by Lander (1996); Cargill et al. (1999), and Chakravarti  (1999).[18]  This hypothesis postulates, roughly, that common conditions are linked to genetic variations that are common in a population.