Describe the relationship between TPMT enzyme activity levels and TGN levels
Describe the relationship between TPMT enzyme activity levels and TGN levels. Be sure to include
supporting data from the graph.
“Pharmacogenetics” by Jeanne Ting Chowning Page 7
Part IV – Putting It All Together From her research, Dr. Ryder hypothesized that patients such as Laura (who became very sick upon receiving the drug) have very high / low TPMT enzyme activity and therefore very high / low levels of TGN nucleotides at normal doses. They easily became sick from the effects of the drug, and could even die. These patients are homozygous / heterozygous for the version of the gene encoding high / low enzyme activity. A better drug dose for these patients is 1/10th the level of other patients.
Patients such as Beth with high / low TPMT enzyme activity had high / low levels of TGN nucleotides. These patients would do well with the drug, and in some cases might even need a larger-than-normal dosage for the treatment to be most effective. These patients were either homozygous for the version of the gene encoding high / low enzyme activity, or were heterozygous.
Based on the graph in Part II, about 10% of the Caucasian population is homozygous / heterozygous.