Thrombocytosis discriminant analysis using an 11-biomarker gene subset. (A) A randomly selected subset of ET (n = 10) and RT (n = 10) patient platelets (each group included 5 males and 5 females) was analyzed by quantitative RT-PCR using oligonucleotide primers specific to each of the 11 genetic biomarkers. Relative gene expression is displayed on a log10 scale standardized to β-actin mRNA, calculated from triplicate wells for each patient sample using the comparative threshold number (Δ-Ct). Boxes represent the interquartile range that encompasses 50% of the values, whereas the 95% confidence intervals and outliers are depicted; the horizontal bar within each box represents the group median; P values were calculated using nonparametric Wilcoxon rank-sum test. (B) LDA plot shows the posterior classification probability of each subject by cohort using the 11-biomarker gene subset based on quantitative RT-PCR profiles (individual group means are delineated by rhomboids with cross-hairs). Cohort 1 included 24 ET and 22 RT patient samples (1 RT sample was omitted because of lack of RNA), whereas cohort 2 included 16 ET and 15 RT patients. For binary decisions (ie, ET or RT), a subject is classified based on the highest posterior classification (ie, a group with probability > .5). Patient samples containing the JAK2V617F mutation (either homozygous or heterozygous) are indicated by +.
