Clinical Value of CASR Gene Polymorphism on Cinacalcet Response in Hemodialysis Patients with Secondary Hyperparathyroidism

Abstract Background Secondary hyperparathyroidism (SHPT) is a common complication of chronic kidney disease (CKD) patients on dialysis, associated with increased cardiovascular mortality and morbidity. Aim to evaluate frequency of variants of CaSR genes related to PTH regulation and to assess the effect of these single nucleotide polymorphisms on cinacalcet response among prevalent hemodialysis patients (HD) with SHPT. Patients and Methods This study included 50 prevalent HD patients with SHPT were recruited from Ain Shams University Hospitals' dialysis units. Clinical stable end-stage renal disease (ESDR) (35 males (70%) and 15 females (30%)), ≥ 18 years old on adequate HD for ≥ 6 months, with intact PTH (iPTH) ≥300 pg/ml and had been treated by cinacalcet. The patient was followed retrospectively for 6 months by measuring serum calcium, phosphorous, alkaline phosphatase, PTH to evaluate the response of cinacalcet. CASR gene and single nucleotide polymorphism (SNP) (rs1042636 and rs1802757) were measured by real-time PCR. Results CASR Gene/SNP rs1042636 (A/G), AA homozygous gene (wild gene) was present in n = 48 (96%) while AG heterozygous gene was present in n = 2 (4%). CASR Gene/SNP rs1802757(C/T), CC homozygous gene (wild gene) was present in n = 42 patients (84%) while CT heterozygous gene was present in n = 6 patients (12%). 21 patients (42%) responded to treatment of SHPT with reduction percent and 29 patients (58%) were non-responding to cinacalcet treatment for 6 months duration. The results showed no significant correlation between CASR gene polymorphism and response to treatment (p-value >0.05). Conclusion There is no statistically significant correlation between single nucleotide polymorphisms (SNPs) of the calcium sensing receptor gene (CASR) and response to cinacalcet as treatment of SHPT among HD patients, for further investigation studies.