The generalisation of a pre-treatment screen for DPD deficiency will exert a substantial effect on the volume of prescriptions of this test and will constitute a challenge in terms of health-care resources.20 Therefore, a comprehensive and accurate knowledge of the distribution of DPD activities and their relationships with DPYD mutations in a large and non-selected population is critical. Here, DPYD is linked to dihydropyrimidine dehydrogenase deficiency.