1040-LBP: Short Tandem Repeat (STR) analysis used to assess biological identity between a potential kidney donor-recipient pair of twins with the patient having a history of Polycystic Kidney Disease

Abstract

Chimerism analysis is an important tool for post-transplant management of allogeneic Stem Cell Transplantation. It is also commonly used for human identity testing in non-clinical settings. In this case, we report the use of this technique to assess identity of a potential kidney donor-recipient pair of twins. Chimerism analysis was performed using 16 STR markers and HLA typing was by intermediate resolution sequence-specific oligonucleotide probes (SSOP). Single Antigen Bead assay by Luminex was performed to determine cPRA. An eighteen-year-old female, with history of autosomal dominant polycystic kidney disease (ADPKD) and hypertension since birth, has a healthy twin sister. Due to this disease, the sick twin underwent a deceased donor kidney transplant. The patient lost graft function due to graft rejection and was restarted on dialysis. She developed a high level of sensitization with cPRA of 99%, and has been on the transplant waiting list for six years. The healthy twin is willing to donate a kidney to her sister and HLA typing of the twins revealed complete identity. However, concerns arose because being twins, the chances of developing the disease could not be underestimated. In order to evaluate the risk of the healthy sister to develop ADPKD, we performed chimerism analysis to determine if these siblings were identical. STR analysis revealed differences between the markers. Our data shows that the patient and her sister are HLA identical, but not identical twins. By using STR analysis, we provided the patient and her family with the prospect to make an informed decision on disease risk as well as the opportunity for the patient to be transplanted with minimal risk of rejection since the patient and her twin are HLA identical.