Senescence is involved in the pathogenesis of chronic obstructive pulmonary disease through effects on telomeres and the anti-aging molecule fibroblast growth factor 23

Fibroblast growth factor-23 rs7955866 polymorphism and risk of chronic kidney disease

Background

A missense gain-of-function fibroblast growth factor-23 (FGF23) gene single nucleotide polymorphism (SNP) (rs7955866) has been associated with FGF23 hypersecretion, phosphaturia, and bone disease. Excess circulating FGF23 was linked with atherosclerosis, hypertension, initiation, and progression of chronic kidney disease (CKD).

Methods

The study included 72 CKD stage 2/3 Egyptian patients (27–71 years old, 37 females) and 26 healthy controls matching in age and sex. Repeated measures of blood pressure were used to quantify hypertension on a semiquantitative scale (grades 0 to 5). Fasting serum urea, creatinine, uric acid, total proteins, albumin, calcium, phosphorus, vitamin D3, intact parathyroid hormone (iPTH), and intact FGF23 (iFGF23) were measured. DNA extracted from peripheral blood leucocytes was used for genotyping of FGF23 rs7955866 SNP using the TaqMan SNP genotyping allelic discrimination method.

Results

Major causes of CKD were hypertension, diabetic kidney disease, and CKD of unknown etiology. There was no significant difference in minor allele (A) frequency between the studied groups (0.333 in GI and 0.308 in GII). Median (IQR) serum iFGF23 was significantly higher in GI [729.2 (531.9–972.3)] than in GII [126.1 (88.5–152.4)] pg/mL, P < 0.001. Within GI, the minor allele (A) frequency load, coded for codominant inheritance, had a significant positive correlation with both hypertension grade (r = 0.385, P = 0.001) and serum iFGF23 (r = 0.259, P = 0.028). Hypertension grade had a significant positive correlation with serum phosphorus and iFGF23.

Conclusions

For the first time in an Egyptian cohort, we report a relatively high frequency of the rs7955866 SNP. It may remain dormant or become upregulated in response to some environmental triggers, notably dietary phosphorus excess, leading to increased circulating iFGF23 with ensuing hypertension and/or renal impairment. Subjects with this SNP, particularly in the homozygous form, are at increased risk for CKD of presumably “unknown” etiology, with a tendency for early onset hypertension and increased circulating iFGF23 out of proportion with the degree of renal impairment. Large-scale population studies are needed to confirm these findings and explore the role of blockers of the renin–angiotensin–aldosterone system and sodium chloride cotransporters in mitigating hypertension associated with FGF23 excess.

Fibroblast growth factor 23 (FGF23) gene polymorphisms are associated with essential hypertension risk and blood pressure levels in Chinese Han population

In this case-control study, 246 EH patients and 157 healthy controls were selected from Chinese Han population to explore the associations between the fibroblast growth factor 23 (FGF23) gene polymorphisms and essential hypertension (EH).The SequenomMassarray system was used for the genotyping of three FGF23 gene Tag single-nucleotide polymorphisms, namely rs7955866, rs13312756, and rs3812822. The primers were designed by Assay Designer 3.1 software, and then the samples were added to a 384-well plate for the polymerase chain reaction amplification, shrimp alkaline phosphatase reaction, and desalting after extension. The distributions of the alleles, genotypes, and haplotypes were compared between the two groups. Confounding factors (sex, age, BMI, smoking, and drinking) were adjusted in the non-logistic regression, and the results showed that rs7955866 and rs3812822 polymorphisms were independently associated with the risk of developing EH (P < 0.05). The statistical analysis of the haplotype of rs7955866-rs13312756-rs3812822 showed that haplotype ACC could increase the risk of developing EH (P = 0.046; OR = 1.513, 95%CI: 1.005-2.278). The analysis of the control group showed that carrying rs7955866 A allele (P = 0.031) and rs3812822 C allele (P = 0.025) was associated with the increase of systolic blood pressure (SBP). The insulin (INS) level in the peripheral blood was significantly different between the case and control groups (P = 0.014). After confounding factors were excluded, the results showed that the serum INS level was also an independent risk factor of developing EH (P = 0.044; OR = 1.604, 95%CI: 1.014-2.539). In summary, our results suggest that FGF23 gene polymorphisms are associated with the risk of developing EH in Chinese Han population.