Put It on the Board
January 2025—The biochemical genetics and molecular technologies laboratories at Mayo Clinic in Rochester, Minn., reported in a recently published study that individuals with a TPMT*1/*8 diplotype displayed reduced thiopurine 6-mercaptopurine metabolism between that of normal metabolizers and intermediate metabolizers, suggesting that TPMT*8 is a reduced-function allele. That allele is common among individuals of African or African American ancestry (approximately 2.3 percent minor allele frequency), the authors write, but is not included in genotyping recommendations owing to its uncertain function.