Background: Recent studies have suggested a correlation between the A986S polymorphism of the calcium sensing receptor (CASR), and serum total and ionized calcium. This study aimed to assess the prevalence of three CASR polymorphisms in a West of Scotland population and relate genotype to serum and urine calcium levels.
Methods: Fasting blood and urine samples were obtained from 121 healthy male and female volunteers aged 20-60 years. Volunteers were genotyped for the A986S, Q1011E and R990G polymorphisms using allele-specific amplification and amplification-created restriction site techniques. Total calcium, ionized calcium and urine calcium excretion were measured using automated clinical chemistry analysers.
Results: Genotype frequencies for the A986S polymorphism were: AA, 74.4%; AS, 24.8%; SS, 0.8%. There was a small but statistically significant (P < 0.01) increase in ionized calcium concentration in AS individuals compared with the wild type (1.22 versus 1.20 mmol/L). No statistical difference was detected in serum total calcium or parameters of urine calcium excretion. Genotype frequencies for the remaining polymorphisms were: RR, 82.6%; RG, 16.5%; GG, 0.8% and QQ, 93.4%; QE, 6.6%; EE, 0%. Biochemical parameters in these individuals were not statistically different from the wild type.
Conclusion: The increase in serum ionized calcium in the AS group was small and, therefore, unlikely to be of clinical significance.
