The receptor for advanced glycation end products (RAGE) has been implicated in the development of vascular complications of diabetes by both in vitro and in vivo studies (1). The most compelling evidence demonstrated that blocking of AGE/RAGE binding prevented atherosclerotic development in animal models (2). It is plausible that genetic differences in the RAGE gene could alter expression and function to affect disease development. In previous studies, we have identified a number of potentially functional polymorphisms: Gly82Ser in the AGE-binding domain (3) and two common promoter polymorphisms at positions −429 and −374 (4). The Gly82Ser polymorphism was not found to relate to micro- or macrovascular disease of diabetes in a number of other studies. However, we reported an association between the −429 polymorphism and retinopathy (4). The relation between genotype at the RAGE promoter and macrovascular disease is unknown.
Therefore, we screened the −429 T/C and −374 T/A polymorphisms in 157 type 2 diabetic subjects with ischemic heart disease (IHD) (107 without myocardial infarction [MI] vs. 51 with MI), 390 nondiabetic subjects with IHD (230 without MI vs. 160 with MI), and 199 control subjects with no personal or family history of diabetes or IHD. Patients with IHD were diagnosed by coronary angiography as having >50% stenosis in at least two coronary vessels. Type 2 diabetes was diagnosed according to World Health Organization criteria. Polymerase chain reaction/restriction fragment–length polymorphism genotyping was performed as previously described (4).
There were no differences in allele frequencies between diabetic subjects with (−429 T 81%, C 19%; −374 T 83%, A 17%) or without (−429 T 83%, C 17%; −374 T 81%, A 19%) macrovascular disease, nor were there any differences between these subjects and control subjects (−429 T 81%, C 18%; −374 T 80%, A 20%) (P > 0.05). In the nondiabetic subjects, no difference was found between subjects with (−429 T 84%, C 16%; −374 T 78%, A 22%) or without (−429 T 81%, C 19%; −374 T 80%, A 20%) MI.
In conclusion, our results demonstrate that in these groups of subjects, no association exists between either the −429 or −374 RAGE promoter polymorphisms and macrovascular disease. Previous functional studies on these polymorphisms indicated an influence on RAGE levels; taken together with the demonstrated role of RAGE in human and animal models of vascular disease, this suggests that an association with vascular disease may be seen, especially in diabetic individuals. These polymorphisms may therefore make either little or no detectable contribution to macrovascular disease or demonstrate the limitations of gene association studies by representing a type II statistical error. As such, larger numbers are required to establish whether these polymorphisms have a causative role in the pathogenesis of vascular disease, demonstrating the possible limitation of gene association studies in case control populations.
This study was supported by the British Heart Foundation (Junior Research Fellowship no. FS/2000007).
Address correspondence to Dr. Barry I. Hudson, Academic Unit of Molecular Vascular Medicine, Research School of Medicine, G Floor, Martin Wing, Leeds General Infirmary, Leeds, LS1 3EX, U.K. E-mail: email@example.com.