Why do you think that there is more variation between patients than shown in the simplified graph?
Challenge question: The actual graph (below) showed much more detail. Why do you think that there is more variation between patients than shown in the simplified graph?
Figure 3. Histogram RBC TPMT frequency distribution histogram for 298 randomly selected Caucasian subjects.
Source: Histogram drawn after top panel of Figure 2 in: Weinshilboum, R.M., and S. Sladek (1980) Mercaptopurine pharmacogenetics: Monogenic inheritance of erythrocyte thiopurine methyltransferase activity. American Journal of Human Genetics 32:651–662.
“Pharmacogenetics” by Jeanne Ting Chowning Page 6
Part III – TPMT Enzyme Activity Levels Dr. Ryder tested Laura, who was very sick, and found that her TPMT enzyme activity level was extremely low.