The Association Between BsmI, ApaI Sites In The Vitamin D Receptor Gene Polymorphism And Patients With Type 2 Diabetic Nephropathy Within A Han Population

Objective:To investigate the association between Bsml, Apal site in the the vitamin D receptor gene polymorphism and type 2 diabetic nephropathy within a Chinese Han population.Methods:Polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) is used to test the genotype and allele frequency of Bsml and Apal polymorphisms in vitamin D receptor gene in 304 patients with type 2 diabetes mellitus (DM group) and 100 normal individuals (normal control group). The DM group was further divided into DNO group (diabetic individuals without nephropathy,122 patients), DN1 (diabetes with small amount of albuminuria,87 patients), DN2 (diabetes with large amount of albuminuria,95 patients), L/NDN (diabetes without nephropathy for over 5 years,83 patients), and EDN (diabetes with nephropathy occurring within first year,64 patients) groups.Result:(1)The genotype and allele frequency of Bsml polymorphis-m had significant difference between DM and NC groups(χ2=7.088, P =0.008;χ2=5.865, P=0.015). The BB+Bb genotype and B allele frequency were significantly higher in DN2 group than in NC group (χ2=14.287, P=0.000;χ2=12.621, P=0.000) and DNO group(χ2=8.063, P=0.005;χ2=8.173,P=0.004). The Apal polymorphism and allele frequency did not show any difference between DM and NC groups. (2)The Bsml BB+Bb genotype and B allele frequency were significantly higher in EDN group than in L/NDN group (χ2=7.228, P=0.007;χ2=5.853, P=0.016). (3)In 182 type 2 diabetic patients with nephropathy, the urine albumin excretion rate was significantly higher in BB+Bb than in bb phenotype(P<0.01). (4)Unconditional logistic regression revealed a correlation between Bsml polymorphism and diabetic nephropathy, with BB+Bb genotype as the risk factor(OR=2.004,95%CI=1.227～3.274). The BB+Bb genotype was also correlated with early diabetic nephropathy(OR=2.394,95%CI=1.032～5.553). Conclusions:The allele B (BB or Bb genotype) in vitamin D receptor gene is correlated with large amount of albuminuria in type 2 diabetes mellitus in a Han population in China, and it is also a risk factor for early diabetic nephropathy in this population.