TCF7L2 (rs7903146) But Not CDKAL1 (rs7754840) Gene Polymorphisms Increase the Risk of New-Onset Diabetes After Kidney Transplant

Objectives: Incidence of new-onset diabetes after transplant negatively affects graft and patient survival. Obesity, impaired fasting glucose before transplant, and a history of diabetes in first-degree relatives are well-defined risk factors. TCF7L2 and CDKAL1 gene polymorphisms have been implicated in the pathogenesis. We investigated the effect of single gene polymorphisms of TCF7L2 (rs7903146) and CDKAL1 (rs7754840) on new-onset diabetes in renal transplant recipients. Materials and Methods: We evaluated 239 renal transplant recipients. TCF7L2 and CDKAL1 gene polymorphisms were assessed by polymerase chain reaction. Results: Mean patient age was 43 ± 13 years. There were 148 male patients (61.9%), and 91 were female (38.1%). New-onset diabetes was detected in 55 patients (23%). In 20 cases (36%), the glycemic disorder was transient; 61% of patients required insulin therapy. In terms of CDKAL1, 108 patients had the wild-type allele, 112 had a single-allele mutation, and 19 had a 2-allele mutation (45.2%, 46.9%, and 7.9%, respectively). In terms of TCF7L2, 163 of the patients had the wild-type allele, 49 had a single-allele mutation, and 27 had a 2-allele mutation (68%, 20%, and 11%, respectively). New-onset diabetes-related factors were age at transplant, body mass index after transplant (calculated as weight in kilograms divided by height in meters squared), tacrolimus, myco- phenolate, and TCF7L2 polymorphism but not CDKAL1 polymorphism. After multiple regression analysis, the effect of TCF7L2 polymorphism persisted. A single allelic change resulted in a risk factor 1.4 times higher for new-onset diabetes after transplant (P = .043; 95% CI, 1.142-1.874) and a double allelic change was 2.7 times higher (P < .01; 95% CI, 1.310-4.073) Conclusions: TCF7L2 (rs7903146) gene polymorphism is an independent risk factor for new-onset diabetes in Turkish renal transplant patients. This study is the first in Turkey to show the distribution and effect of these genes in kidney transplant patients.