Chronic Transplant Glomerulopathy and Regulation of Expression of Ephrin B1

Inclusion Criteria: * Kidney transplant patient for whom renal biopsies are stored in the "collection of the University Hospital Toulouse" (collection N° DC-2009-989) and who received information on the purpose of the study, use of biopsies and who has not manifested any opposition. * Kidney transplant patient with iterative biopsies with at least: post-surgery biopsy D0 (or early post-transplant biopsy D7 and at least one biopsy protocol. - Age\> 18 years Case group: - Kidney transplant patient, followed up by "organ transplant unity" of CHU Toulouse, with antecedent of CMR progressing to CTG between 2006 and 2013. Control group: - Kidney transplant patient, followed up by "organ transplant unity" of CHU Toulouse, with antecedent of CMR without progressing to CTG between 2006 and 2013 Exclusion Criteria: * patient with uncontrolled hypertension - patient with diabetes mellitus - * patient treated or who was treated with mTOR inhibitor - recurrence of the initial glomerular pathology - de novo glomerulopathy - patient including in another study with an exclusion period still going