Investigation of angiotensin-1 converting enzyme 2 gene (G8790A) polymorphism in patients of type 2 diabetes mellitus with diabetic nephropathy in Pakistani population
Authors: Younas Hooria , Ijaz Tahira , Choudhry Nakhshab 
Published: February 2022

Background
Type 2 diabetes mellitus is a multifactorial disease that escalates the risk of other associated complications such as diabetic neuropathy, retinopathy, and nephropathy. Diabetic nephropathy is a microvascular condition that leads to end-stage renal disease (ESRD). There are several genes involved in disease development and it is a challenging task to investigate all of these. Nonetheless, identifying individual gene roles can assist in evaluating the combinatorial effects with other genes. Angiotensin-1 converting enzyme 2 (ACE2), is the key regulator of blood pressure in the Renin-Angiotensin-Aldosterone System that hydrolyzes angiotensin II (vasoconstrictor) into angiotensin 1–7 (vasodilator). The association of different variants of the ACE2 with the risk of type 2 diabetes mellitus has been determined in various populations with susceptibility to other complications. This study was aimed to investigate the association of Angiotensin-1 converting enzyme 2 polymorphism, G8790A, with the increased risk of type 2 diabetes mellitus (T2DM) development with the complication of diabetic nephropathy (DN) in the Pakistani population.

Methods
In this case-control study, a total of 100 healthy controls and 100 patients of type 2 diabetes mellitus aged > 40 years, having disease duration ≥ 10 years were compared. The G8790A polymorphism in ACE2 was analyzed by allele-specific polymerase chain reaction (AS-PCR). The urinary albumin excretion (UAE), urinary creatinine, and albumin to creatinine ratios (ACR) were determined to assess renal function status. Pearson bivariate correlation coefficients were calculated to investigate the relationship among all the parameters. Crude and adjusted odds ratios were found to determine any risk association between ACE2 G8790A polymorphisms and disease development. The p-values < 0.05 were considered significant.

Results
A homogeneity was obtained regarding the distribution of data by sex, BMI, diastolic blood pressure, pulse rate and urinary creatinine levels between case and control groups. The ACR showed a significant correlation with UAE (r = 0.524, p = 0.001), urinary creatinine (r = -0.375, p = 0.001) and random blood sugar levels (r = 0.323, p = 0.005) with the complication of diabetic nephropathy in T2DM patient. Females with the AA genotype had a 10-fold increased risk for the development of type 2 Diabetes (OR = 9.5 [95% CI = 2.00–21.63] p<0.002). Males having A allele showed a significant association for susceptibility of type 2 Diabetes (OR = 3.807 [95% CI = 1.657–8.747] p<0.002). However, none of the genotypes or alleles revealed an association for diabetic nephropathy in male and female patients. Urinary ACR was also found to be positively correlated with UAE (r = 0.642 p = 0.001 & 0.524, p = 0.001) and random blood sugar levels (r = 0.302, p = 0.002 & r = 0.323, p = 0.005) in T2DM and T2DM+DN groups, respectively.

Conclusion
The study finding indicated that female AG/AA genotype and male A genotype of G8790A polymorphism in the ACE2 gene were associated with type 2 diabetes mellitus as a genetic risk factor but are not associated with diabetic nephropathy in the Pakistani population.