Distribution of JAK2 V617F array-based allele burden scores. Scores should be monotonically related to the proportion of the mutant allele in the DNA sample but were not calibrated. Individuals with evidence of UPD are shown as red circles. (A) Scores among MPN research initiative participants, stratified by self-reported mutation status (V617F-negative [-] or V617F-positive [+]). (B) Scores among population controls not enrolled in the MPN research initiative, stratified by age. The red dashed line represents the threshold used to classify V617F carriers in the analysis. Inf, infinity.