Introduction: Previous case-control studies have suggested that the –1562C/T and R279Q polymorphisms of the matrix metalloproteinase 9 gene (MMP9) are associated with coronary heart disease (CHD). However, other studies do not confirm these relationships. The objective is to assess these relationships using meta-analysis. Methods: Databases, including PubMed and ScienceDirect, were searched to access the genetic association studies. Then data were extracted. Pooled odds ratio (OR) and 95% confidence interval (CI) were calculated. Moreover, subgroup and sensitive analysis were performed. Results: The meta-analysis of the –1562C/T polymorphism included 12 studies with 8,336 cases and 3,984 controls. The –1562T allele was significantly associated with CHD (OR 1.25, 95% CI 1.08–1.45, p = 0.004). There was heterogeneity among the 12 studies (I2 = 61%, p = 0.003). The overall results were consistent and were not changed substantially by the removal of any data set. The meta-analysis of the R279Q polymorphism, including 6 studies with 6,983 cases and 3,282 controls, showed that the R279Q polymorphism was not associated with CHD (p = 0.16). Conclusions: The synthesis of available evidence supports the fact that the MMP9 –1562C/T polymorphism is a risk factor for CHD.

Diabetic nephropathy (DN) is one of the most serious chronic complications of diabetes mellitus. The observed incidence patterns in different ethnics and familial clustering have suggested that the genetic factor plays an important role in the development and progression of DN. This paper reviews the recent advances on genetics of DN, including candidate genes association studies, linkage studies and genome-wide association studies (GWASs). Candidate genes association studies and meta-analysis showed that a few candidate genes have been reproducibly associated with DN, such as ACE, AGT and PPARG genes. Linkage studies and genome-wide linkage studies have also identified susceptibility chromosomal loci. With the development of high-throughput sequencing and chip techniques, GWAS has become an important strategy to identify variants responsible for DN. The genetic factor has been the significant contribution to the pathobiology of DN. However, it is not the only cause of the pathobiology of DN, because the environment factor also influences the pathobiology of DN. Nonetheless, genetic studies may provide valuable information for the pathobiology of nephropathy and potential targets of its treatment.