Association of the calcitonin gene (CA) polymorphism with bone mass and bone responsiveness to hormone therapy in postmenopausal Korean women

Abstract

To evaluate the relationship between cytosine-adenine (CA) polymorphism of the calcitonin gene, serum calcitonin levels, bone mineral density (BMD) and bone responsiveness to hormone therapy (HT). Calcitonin (CA) polymorphism, serum calcitonin, and BMD at the lumbar spine and proximal femur were determined in 430 postmenopausal Korean women. In all, 181 women were treated with sequential HT for 2 years. Four major calcitonin alleles were present with a frequency greater than 5%: 122 base pair (bp) 61.3%, 108 bp 25.1%, 110 bp 7.0%, and 124 bp 6.2%. There were no differences in the BMD at the lumbar spine and proximal femur in postmenopausal women with zero, one, or two copies of major alleles. Serum calcitonin levels in women with two copies of the 108 bp allele were significantly higher than those in women with zero or one copy of the 108 bp allele. The annual rate of positive change of BMD at the femoral neck after HT was significantly higher in women homozygous for the 108 bp allele than in women with zero or one copy of the 108 bp allele, but the number of copies of the major calcitonin alleles was not significantly associated with HT-responsiveness. The calcitonin (CA) polymorphism is one of the genetic factors that may affect BMD changes at the femoral neck after HT in Korean women.