Association of genetic variants in the promoter region of genes encoding p22phox (CYBA) and glutamate cysteine ligase catalytic subunit (GCLC) and renal disease in patients with type 1 diabetes mellitus
1 Laboratório de Endocrinologia Celular e Molecular (LIM-25), Faculdade de Medicina da Universidade de São Paulo. Av. Dr. Arnaldo, 455 #4305, 01246-903, São Paulo-SP, Brazil
2 Hospital do Servidor Público Estadual (HSPE), Rua Pedro de Toledo, 1800, 04039-901. São Paulo-SP, Brazil
3 Divisão de Endocrinologia, Hospital das Clínicas, Faculdade de Medicina da Universidade de São Paulo. R. Dr. Eneas de Carvalho Aguiar, 647, 05403-000, São Paulo-SP, Brazil
4 Centro de Diabetes, Universidade Federal de São Paulo. R. Cel. Lisboa, 826, 04020-041, São Paulo-SP, Brazil
5 Divisão de Endocrinologia, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, R. Ramiro Barcelos, 2350, 90035-903, Porto Alegre-RS, Brazil
6 Divisão de Endocrinologia, Departamento de Clínica Médica, Faculdade de Medicina da Universidade Estadual de Campinas (UNICAMP), Rua Tessália Vieira de Camargo, 126, 13084-971. Campinas-SP, Brazil
7 Laboratório de Gastroenterologia Clínica e Experimental (LIM 07), Faculdade de Medicina da Universidade de São Paulo, Av. Dr. Arnaldo, 455, # 4384, 01246-903, São Paulo-SP, Brazil
BMC Medical Genetics 2011, 12:129 doi:10.1186/1471-2350-12-129Published: 30 September 2011
Oxidative stress is recognized as a major pathogenic factor of cellular damage caused by hyperglycemia. NOX/NADPH oxidases generate reactive oxygen species and NOX1, NOX2 and NOX4 isoforms are expressed in kidney and require association with subunit p22phox (encoded by the CYBA gene). Increased expression of p22phox was described in animal models of diabetic nephropathy. In the opposite direction, glutathione is one of the main endogenous antioxidants whose plasmatic concentrations were reported to be reduced in diabetes patients. The aim of the present investigation was to test whether functional single nucleotide polymorphisms (SNPs) in genes involved in the generation of NADPH-dependent O2•- (-675 T → A in CYBA, unregistered) and in glutathione metabolism (-129 C → T in GCLC [rs17883901] and -65 T → C in GPX3 [rs8177412]) confer susceptibility to renal disease in type 1 diabetes patients.
401 patients were sorted into two groups according to the presence (n = 104) or absence (n = 196) of overt diabetic nephropathy or according to glomerular filtration rate (GFR) estimated by Modification of Diet in Renal Disease (MDRD) equation: ≥ 60 mL (n = 265) or < 60 mL/min/1.73 m2 (n = 136) and were genotyped.
No differences were found in the frequency of genotypes between diabetic and non-diabetic subjects. The frequency of GFR < 60 mL/min was significantly lower in the group of patients carrying CYBA genotypes T/A+A/A (18.7%) than in the group carrying the T/T genotype (35.3%) (P = 0.0143) and the frequency of GFR < 60 mL/min was significantly higher in the group of patients carrying GCLC genotypes C/T+T/T (47.1%) than in the group carrying the C/C genotype (31.1%) (p = 0.0082). Logistic regression analysis identified the presence of at least one A allele of the CYBA SNP as an independent protection factor against decreased GFR (OR = 0.38, CI95% 0.14-0.88, p = 0.0354) and the presence of at least one T allele of the GCLC rs17883901 SNP as an independent risk factor for decreased GFR (OR = 2.40, CI95% 1.27-4.56, p = 0.0068).
The functional SNPs CYBA -675 T → A and GCLC rs17883901, probably associated with cellular redox imbalances, modulate the risk for renal disease in the studied population of type 1 diabetes patients and require validation in additional cohorts.