A986S Polymorphism Research Articles

Serum calcium, urine calcium and polymorphisms of the calcium sensing receptor gene

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. 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. 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. The increase in serum ionized calcium in the AS group was small and, therefore, unlikely to be of clinical significance.

Role of intron 5 C/T polymorphism of the calcium sensing receptor gene in the regulation of the serum FSH and LH in post-menopausal women

High extracellular calcium concentration (Cao(2+)) acts to inhibit calcium sensing receptor (CaR) signalling on cellular surfaces in parathyroid glands. This receptor is, however, also expressed on the membranes of some non-calciotropic endocrine cells, including pituitary-derived cells. The aim of our study was to analyse relationships between the CaR gene and the circulating FSH and LH in normal post-menopausal women. A total of 95 untreated euparathyroid post-menopausal women were investigated in the study. The serum FSH and LH levels were evaluated in relationship to allele combinations of the CaR gene (C/T polymorphism in the intron 5 and A986S polymorphism in exon 7), using an analysis of co-variance (ANCOVA) model. Distribution of TT, TC and CC allele combinations (intron 5 C/T polymorphism) was 51, 43 and 6 %, respectively. Higher serum FSH and LH levels were found in carriers of C allele than in women without this allele (p < 0.002 and p < 0.03, respectively). No correlations were found between A986S polymorphism and serum FSH and LH levels. Serum FSH and LH levels are associated with intron 5 C/T (but not A986S) polymorphism of the CaR gene in untreated post-menopausal women. The physiological role of the CaR gene in the regulation of the gonadotropic function needs to be further investigated.

Calcium-sensing receptor (CASR) A986s polymorphism and bone disease in primary biliary cirrhosis and Wilson disease

Background/Aim: Genetic factors have been implicated in the pathogenesis of osteoporosis, a common disorder in primary biliary cirrhosis (PBC) and decreased bone mineral density (BMD) with elevated serum osteoprotegerin and beta-cross-laps was described by our group in Wilson disease (WD). The CaSR “A986S“ genotype was shown to affect serum Ca2+ levels, and an association between the polymorphism and BMD was reported. Our aim was to investigate the A986S CaSR polymorphism and BMD in Hungarian PBC and WD patients.

Calcium-sensing receptor gene polymorphism is not associated with bone mineral density in Italian postmenopausal women.

Calcium-sensing receptor (CaR) is a candidate gene for osteoporosis susceptibility. Several CaR polymorphisms have been identified and an association between the A986S genotype and serum calcium levels has been found in Canadian postmenopausal women. We investigated whether the presence of 986S allele was associated with bone mineral density (BMD) and osteoporotic fractures. The study group consisted of 164 Italian postmenopausal women without fragility fracture (Fx(-)) and 55 women with fracture (Fx(+)). A fragment of exon 7 of CaR gene containing three polymorphisms (A986S, R990G and Q1011E) was amplified by PCR and sequenced. Anthropometric characteristics and BMD were evaluated. The A986S polymorphism was the most commonly observed (27.9%), whereas the other two CaR polymorphisms, R990G and Q1011E, occurred in a minority of cases (8.8 and 5.5% respectively). There was no significant difference in the frequency distribution of any CaR allele between Fx(-) and Fx(+) patients. Body mass index was found to predict BMD at the lumbar spine and femoral neck. The A986S polymorphism and Years since menopause were not independent predictors of BMD at any site. As far as fracture occurrence, there was no statistically significant difference in the prevalence of fractures between women carrying or not carrying the 986S allele. Our data do not support a role of A986S CaR polymorphism in BMD and in the prevalence of fragility fractures in Italian postmenopausal women.

Lack of association between the calcium-sensing receptor (CaSR) A986S polymorphism and colorectal cancer

Lack of association between the calcium-sensing receptor (CaSR) A986S polymorphism and colorectal cancer

Calcium-sensing receptor gene polymorphisms in primary hyperparathyroidism

The calcium-sensing receptor (CaR) polymorphism A986S has been found to be associated with higher serum calcium levels in normal subjects, suggesting that this amino acid change might decrease the inhibitory activity of the mutated receptor, render the parathyroid cells more prone to proliferate, and eventually increase the risk of developing primary hyperparathyroidism (PHPT). The aim of the present study was to investigate the frequency of this and other 2 known CaR polymorphisms (R990G and Q1011 E) in patients with PHPT and their effect on its phenotype. We studied 103 Italian patients with PHPT and 148 healthy Italian subjects and we compared the results in 50 pairs matched for sex, age and geographic provenience. A fragment of exon 7 of the CaR gene, containing the 3 polymorphic loci of interest (A986S, R990G, and Q1011E), was amplified by PCR and sequenced. Serum calcium and PTH levels, BMD and other biochemical and clinical parameters were evaluated. The frequency distribution of the A9865, R990G, and Q1011 E polymorphisms in the 103 PHPT patients was 39.8%, 5.8%, and 2.0%, respectively. There was no difference in the frequency of the 3 CaR polymorphisms in the 50 matched pairs of patients and controls. We found no significant difference in several clinical and biochemical parameters between PHPT patients carrying or not the 986S allele. Finally, no relationship was observed between the 986S genotype and total and ionized serum calcium in control subjects. The A986S CaR polymorphism is the most common in Italian PHPT patients and the allotype AS does not appear to play a relevant role in the pathogenesis of PHPT and its severity. The A986S polymorphism does not correlate with serum calcium levels in normal Italian subjects.

Calcium-sensing receptor A986S polymorphism in human rectal cancer.

In vivo and in vitro experiments show the protective role of calcium ions (Ca2+) against colorectal cancer. The calcium-sensing receptor (CaSR) detects extracellular Ca2+ concentration. An association between the CaSR A986S polymorphism and serum calcium in healthy adults has been reported. Subjects with AA genotype had lower serum concentrations of Ca2+ than other genotypes. The expression of erbB-2, epidermal growth factor receptor (EGFR), p53, and ras in colorectal cancer has been suggested to have diagnostic and prognostic significance. We investigated the relationship between the CaSR A986S polymorphism and the expression of erbB-2, EGFR, p53, and ras as well as the UICC stage in 56 patients with rectal cancer. The occurrence of the genotype AA was not different in cancer patients and in 112 controls. In the presence of the coexpression of major oncogenes, patients with genotype AA were in significantly higher UICC stages than in the case of AS genotype. During the follow-up period AA genotype showed a tendency for poor prognosis. Our observation raises the possibility that genetic alterations of CaSR influence the pathogenesis of rectal cancer.