Analysis of genetic and clinical risk factors of post-transplant thrombocytopenia in kidney allograft recipients.

Background: Hematological abnormalities after transplantation are complications that may arise after renal transplantation, of which thrombocytopenia is associated with increased risk of bleeding and other complications. The development of thrombocytopenia is affected by various clinical conditions, and the stromal-derived factor 1 (SDF1) and platelet factor 4 (PF4) genes are known to be involved in the production or destruction of platelets. The purpose of this study was to investigate the prevalence of posttransplant thrombocytopenia and its association with other clinical conditions and genetic polymorphisms of SDF1 and PF4 genes a long time after transplantation.

Methods: This is a retrospective study that includes a total of 305 kidney transplant (KT) recipients between 2008 and 2012 at St. Vincent Medical Center, Los Angeles, CA. In this study, posttransplant thrombocytopenia was defined as a 30% reduction in platelet count from the baseline in the first week or a decrease of <100 (×10/μL) within 1 year after KT. The subjects were divided into posttransplant thrombocytopenia and control groups. The chi-square test, t-test, and logistic regression were used for the analyses.

Results: In the first week, 65 patients had a 30% reduction in platelet count (21.3%). Gender, simultaneous kidney-pancreas transplantation, induction therapy (IT), and only alleles of rs2297630 of SDF1, among the SDF1 and PF4 genes, showed statistically significant differences. The rs2297630 alleles were consistently significant risk factors (non G vs. G: odds ratio = 0.445; 95% confidence interval, 0.224-0.884; p = .021) in the multiple logistic regression. In the 1-year study, 61 patients (20.0%) had platelet counts of <100 × 10/μL and had statistically significant differences in patients who had delayed graft function and induction therapy.

Conclusions: In this study, non-G group of rs2297630 in SDF1 significantly increased the risk of post-transplant thrombocytopenia in the first week of kidney transplantation.