JAK2 and myeloproliferative disorder: Moreover, the familial MPN cohort exhibits enrichment for individuals carrying more than three risk alleles (counting one for heterozygotes and two for homozygotes; Supporting Information Figure 1) and a trend for odds ratios increasing toward double positive (TERT/JAK2) individuals (Supporting Information Table 2), further supporting the possibility of JAK2 GGCC contributing to MPN familial clustering.