SLC2A9 Genotype Distribution and Left Atrium Diameter in Patients with Arterial Hypertension and Atrial Fibrillation

BACKGROUND: In recent years, asymptomatic hyperuricemia (HU) has been found to have significant adverse effects on the cardiovascular system. Uric acid (UA) accumulation in cardiomyocytes may cause ionic and structural remodeling of the atria. One of the causes of increased UA and a significant risk factor for HU is polymorphism in the SLC2A9 gene, which encodes the GLUT9 protein, a highly specific urate transporter in proximal renal tubular cells.

AIM: To investigate the frequency of genotypes and alleles of the SLC2A9 gene rs734553 polymorphism and left atrium (LA) diameter in patients with arterial hypertension (AHT) and atrial fibrillation (AF).

MATERIALS AND METHODS: One hundred four patients, including 94 (90.4%) men and 10 (9.6%) women (aged 55 [45; 61] years old) were enrolled in the study. The patients were divided into the following groups: first — patients with AF (n = 13); second — patients with AHT and AF (n = 68); and third — patients with AHT (n = 23). The LA diameter equal to the LA anterior–posterior dimension on transthoracic echocardiography was taken into account as a characteristic of structural changes of the LA. All patients underwent instrumental, laboratory, and molecular genetic testing, including SLC2A9 gene rs734553 polymorphism using the polymerase chain reaction technique.

The data were presented as median, first and third quartiles, and absolute and relative frequencies. Differences between groups of patients were assessed using the Mann – Whitney U-test and Fisher and Pearson’s χ² test. The Kruskal–Wallis test was used to compare three independent groups. Differences were considered statistically significant at p < 0.05. The relationship between the quantitative and dichotomous variables was described using the rank-biserial correlation coefficient (rrb). The distribution of alleles and genotypes in the studied patient groups was tested for Hardy – Weinberg equilibrium and assessed using the χ² test.

RESULTS: There were no significant differences (p > 0.05) when comparing the LA diameter and the genotype of the SLC2A9 gene rs734553 polymorphism in all groups of patients. However, in Group 2, the LA diameter in the CC genotype (43 [42; 44] mm) patients and the AC genotype (40 [49; 43] mm) patients was determined to be larger than in the AA genotype ones (38 [38; 42] mm). In Group 1, the LA diameter in the AC genotype patients (40 [38; 42] mm) was larger than in the AA genotype ones (38 [34; 38] mm).

When studying the distribution frequency of genotypes and alleles of the SLC2A9 gene rs734553 polymorphism in patients with LA dilatation, we found that in the second group of patients, the AC genotype was significantly more common than in other groups (23.5%) (p = 0.004), and there was also a trend toward a higher incidence of AA (13.2%) and CC (14.7%) genotypes. However, it did not reach the criteria for statistical significance. It should be noted that in patients of the first group, LA dilatation was diagnosed only with the AC genotype (38.5%). Dilatation of the LA in patients of the third group was not detected.

CONCLUSIONS: In Group 1 patients (with AF), LA dilatation was observed only in the AC genotype ones. In Group 2 patients (with AHT and AF), LA dilatation was significantly more frequent (p = 0.004) in the AC genotype ones. The AC and CC genotype of the SLC2A9 gene rs734553 polymorphism was more frequent in Group 2 patients (with AHT and AF).