P117 Swapping the swab for bmt confirmatory typing

Abstract

Aim Our lab switched from ACD blood source to buccal swab source for confirmatory typing of HSCT (Hematopoietic Stem Cell Transplantation). The buccal specimen source met our goals for a second sample source and determining true homozygosity versus allele drop out. We will discuss implementing the change and a case of HLA-DQB1 drop out. Methods Primary typing of HLA low resolution (Sequence Specific Oligonucleotide, One Lambda) and high resolution typing (SeCore, One Lambda) are completed on ACD blood. Implementation of the buccal swab in our lab included validation of a new extraction kit, standard operating procedural (SOP) changes, test code/resulting changes, and training. Results Validation and integration of the EZ1 DNA Tissue kit (Qiagen) were simple to complete. SOP changes and resulting added the process to include referencing the white blood count (WBC) within the week of the blood collection for the primary typing. Primary typing results homozygous at any loci accompanied with a WBC great than 10 × 10(9)/L, triggers a closer look with the buccal sample. An obstacle we encountered was the collection of the buccal leading to low amounts of DNA for testing. We provided feedback to our collection groups and have observed fewer re-collections the past year. A difference observed between blood and buccal swab was for a patient’s DQB1 locus. SSO/SeCore from blood sample demonstrated homozygous DQB1 ∗ 05. DRB1 resulted ∗ 01, ∗ 04; therefore, we more commonly expected a second DQB1 antigen other than ∗ 05. The WBC result from the blood collection date was 57.7 × 10(9)/L. We obtained DNA from buccal sample and re-tested. Assays now cleanly demonstrated heterozygous DQB1 ∗ 05, ∗ 03. Conclusion Switching sample sources created process changes for the laboratory and the collection group. Training and process flow in the lab was successful. Feedback to the collection group was needed to ensure swabbing was adequate for a good DNA yield for testing. We feel the testing algorithm provides assurance of accurate test results for HSCT patients.