Relatively few studies have been performed evaluating the variant allele frequencies in Spanish populations. To date, no studies evaluating the TPMT variant allele frequency in the Hispanic population have been reported. Hispanics are a growing part of the patient population treated in the United States. Characterization of the proportion of patients with variant genotypes in this population is important since Hispanic children represent a significant proportion of children being treated with thiopurines.
A single 3 cc heparinized blood sample will be obtained for TPMT genotyping. The sample will be obtained either simultaneously with a clinical sample, at the time of an otherwise medically indicated intravenous catheter placement or scavenged from excess blood remaining following clinical laboratory testing.
