Calcium metabolism and endocrine functions in a family with familial hypocalciuric hypercalcemia.

OBJECTIVE: We report two Hungarian patients with familial hypocalciuric hypercalcemia (FHH) caused by a mutation of the calcium-sensing receptor (CaSR) at codon 55. The proband and her father were heterozygous for this mutation. DESIGN: We performed detailed clinical and laboratory assessments of this family to characterize the effects of CaSR mutation on several endocrine organs expressing CaSR. RESULTS: Interestingly, we could not detect any failure in the function of any tissues we examined, except in serum calcium levels. CONCLUSIONS: To our knowledge, this has been the first report from Eastern and Central Europe showing P55 L mutation of the CaSR, as well as the first publication discussing the effect of this mutation on several endocrine systems containing CASR.

Lack of association between calcium-sensing receptor gene "A986S" polymorphism and bone mineral density in Hungarian postmenopausal women.

Calcium-sensing receptor (CaSR) is an attractive candidate gene for osteoporosis susceptibility. The CaSR "A986S" genotype has been shown to have an effect on serum calcium. Recently, an association has been reported between the CaSR gene A986S polymorphism and bone mineral density in healthy white girls. In this study, we examined whether CaSR gene A986S polymorphism is associated with decreased bone mass in 230 Hungarian postmenopausal women. From this cohort, 108 osteoporotic patients were compared with 122 healthy control women. Bone mineral density (BMD) was measured at the lumbar spine (L2-4) and femoral neck using dual-energy X-ray absorptiometry. Allele-specific polymerase chain reaction was used to amplify A986S polymorphisms of the CaSR gene. We found no difference in the distribution of different alleles or genotypes between groups (p = 0.762). No significant effect of CaSR genotype on BMD was observed either in the whole population or in the subgroups. Our data do not support the idea that CaSR gene A986S polymorphism has an impact on bone mass.

Lack of association between interleukin-1 receptor antagonist protein gene polymorphism and bone mineral density in Hungarian postmenopausal women.

The major determinant for risk of osteoporosis in later life is bone mineral density (BMD) attained during early adulthood. Bone mineral density is a complex trait that is presumably influenced by multiple genes. Interleukin-1 receptor antagonist protein (IL-1RN) is an attractive candidate gene for osteoporosis susceptibility, because IL-1RN completely inhibits the stimulatory effects of interleukin-1 (IL-1) on bone resorption in organ cultures and has been implicated in the pathogenesis of osteoporosis. In addition, the IL-1RN gene contains a variable-number tandem repeat polymorphism (VNTR) in intron 2 with three potential protein-binding sites. Recently, an association has been found between this polymorphism and postmenopausal bone loss in the spine. In this study, we use the previously described IL-1RN polymorphism to test for an association between this polymorphism and bone mineral density in our population of postmenopausal women. There was no correlation between alleles or genotypes and BMD in the 286 subjects. Dividing subjects into osteoporotic and healthy groups (osteoporotics and controls), we found no difference in the distribution of alleles or genotypes between groups. We found no association between IL-1RN alleles or genotypes and BMD either at the lumbar spine or the femoral neck within groups. Our data do not support the hypothesis that this IL-1RN gene VNTR polymorphism has an impact on bone mass in postmenopausal women.