Abstract
Introduction: Secondary hyperparathyroidism (SHPT) is a common complication associated with morbidity and mortality among hemodialysis (HD) patients.
Objectives: The current study aims to evaluate the frequency of CASR gene polymorphism variants related to parathyroid hormone (PTH) regulation (CASR rs1042636 and CASR rs1802757) and to test the hypothesis that single nucleotide polymorphisms (SNPs) in the CASR gene alter the response to cinacalcet among Egyptian HD patients with SHPT.
Patients and Methods: A case-control study that included 50 HD patients with intact parathyroid hormone (iPTH) ≥300 pg/mL treated with cinacalcet for a 6-month duration and 40 healthy volunteers as a control group. Eligible patients were recruited from Ain Shams university hospitals. Blood samples were collected from patients and controls to assess allele frequencies of CASR gene polymorphism variants using real-time polymerase chain reaction (PCR), corrected calcium (Ca), phosphorus (P), Ca×P product, iPTH level, and alkaline phosphatase before and after treatment. HD patients were categorized into two groups based on the reduction percentage; responders’ patients (iPTH ≥20%) and non-responders to cinacalcet treatment.
Results: Of 50 HD patients, 48 (96%) carried the rs1042636 AA wild gene, while only two (4%) carried the rs1042636 AG mutant gene, 42 (87.5%) carried the rs1802757 CC wild genotype, and 6 (12.5%) carried the CT mutant genotype. The minor alleles T and G were (6.3% and 2%) respectively, with no statistically significant difference between the patient and control groups regarding the CASR genotypes or alleles distribution. There was no significant difference between responders and non-responder’s patient groups regarding CASR genotypes or allele frequencies. Moreover, no significant correlation between CASR genotypes or alleles to delta change of Ca, P, Ca×P product, or PTH was seen. However, CASR rs1802757 CT mutant genotype was associated with a significant reduction in alkaline phosphatase levels after treatment.
Conclusion: There is no significant association between the gene polymorphism CASR rs1042636 or CASR rs1802757 and the reduction in PTH levels as a response to cinacalcet treatment among Egyptian HD patients with SHPT.