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The tendency for Afro-descendant individuals with hypertension to retain salt and water can lead to low-renin hypertension. APOL1 G1 and G2 risk variants have been linked to earlier diagnosis of hypertension and renal disease progression in patients with chronic kidney disease attributed to hypertension. To investigate this phenomenon, a prevalence study was conducted.
Adult patients from south-west Colombia diagnosed with hypertension were recruited as volunteers in a primary care centre from Cali, Valle del Cauca. Their serum levels of total renin and aldosterone concentration were measured, and their phenotypes were classified based on their renin and aldosterone levels. The phenotypes were categorized into low renin and aldosterone phenotype, low renin and high aldosterone phenotype, and high renin and aldosterone phenotype. The buffy coat samples for DNA extraction and the associated data from the same individuals diagnosed with hypertension were provided by the Biorrepositorio from Fundación Valle de Lili with the appropriate approval of the IRB Biomedical Research Ethics Committee. APOL1 G1 and G2 risk variants were genotyped through conventional sanger sequencing. African ancestry was determined according to the genetic sequence of the mitochondrial DNA D-Loop via sanger sequencing.
79 patients were included in the study (mean age 55 [SD 8], 47% male). The study found a prevalence of 41% of patients with low renin and aldosterone phenotype, 25% with low renin and high aldosterone phenotype, and 34% of patients with high renin and aldosterone phenotype. The patient's sodium intake was found to be 8200 mg/day. The study also found that 39% of patients were taking less than 3 medications despite being formulated with more.
The APOL1 recessive model was applied. The prevalence of the high-risk APOL1 genotype in the cohort was 10.12% (8 individuals), equivalent to the known prevalence of the high-risk APOL1 genotype in Black Americans. The overall allele frequencies for G0, G1 and G2 were 70.25%, 17.09% and 12.66%, respectively, comparable to other populations. The APOL1 status was G0/G0 in 40 participants (49.1%), G0/G1 or G0/G2 in 31 participants (39.24%), G1/G1 in 4 participants (5.06%) and G2/G2 and G1/G2 both in 2 participants (2.53% each). When comparing the baseline characteristics of patients with two APOL1 risk alleles with those with zero or one risk allele, there were no significant differences in age, sex, body mass index or diabetes mellitus. There were no differences in the renin aldosterone phenotypes between the groups (p-value 0.3)
The APOL1 allelic frequencies were equivalent to the frequencies of other populations. Moreover, the prevalence of the high-risk APOL1 genotype in the cohort was comparable to the known prevalence of the high-risk APOL1 genotype in Black Americans. The participants with low risk APOL1 genotypes were indistinguishable from the high risk APOL1 genotypes. Studies with a larger sample are needed to validate any possible association.