Is the Val617Phe JAK2 mutation a predisposing factor to the occurrence of familial MPD?
The genotyping of the JAK2 mutation in a subgroup of 46 families with at least 2 affected patients with PV, ET, or MMM revealed 3 groups of families (Figure 2A). The first subgroup (6 families; 13%) consisted of families in which the JAK2 mutation was detected in none of the MPD patients. This subgroup included 4 families with only ET patients and 2 families with only PV patients (Figure 2B). In the second subgroup, including 18 (39%) families, the distribution of the JAK2 mutation was heterogeneous. These families had at least 1 patient with the JAK2 mutation and 1 or 2 affected relatives without the JAK2 mutation. In these heterogeneous families, the absence of the JAK2 mutation was not strictly but preferentially associated with ET (13 of 18). Last, in 22 (48%) families, all affected MPD patients had the JAK2 mutation detectable in their blood mononuclear cells. This subgroup included families with a single MPD type (59%) as well as families with several types (41%). In these famili
