Association of plasminogen activator inhibitor-1 genotype with avascular osteonecrosis in steroid-treated renal allograft recipients1

BACKGROUND The mechanism of avascular osteonecrosis (AVN) is controversial. Besides an increased bone marrow pressure with reduced blood supply, an enhanced coagulation has been considered. We hypothesize that a genetic variant of the plasminogen activator inhibitor-1 (PAI-1) determines the risk of AVN in glucocorticoid-treated patients. METHODS Genotyping for the 4G/5G PAI-1 polymorphism was performed in 228 glucocorticoid-treated renal transplant patients. AVN of the hip was present in 26 patients. Magnetic resonance imaging (MRI) of the hips was obtained in 81 of the remaining renal transplant patients without clinical symptoms of AVN. RESULTS The presence of the homozygous 4G/4G PAI-1 genotype was higher in patients with AVN (60.3%) as compared with patients without either clinical (20.6%, P