Relationship between SP1 polymorphism and osteoporosis in beta-thalassemia major patients

beta-Thalassemia is an autosomal recessive disease characterized by defective beta-globin chain production. Osteoporosis is an important cause of morbidity in patients with beta-thalassemia major. The pathogenesis of reduced bone mineral density (BMD) is multifactorial. A range of genetics factors have been implicated in other populations of patients with osteoporosis. Polymorphism at the Sp1 binding site of the collagen type I A1 (COLIA1) gene is thought to be an important factor in the development of osteoporosis.

Alleles S and s, detected by presence of a G or T nucleotide, respectively in a regulatory site of the COLIA1 gene were investigated in 37 beta-thalassemia major patients with osteoporosis and 92 controls without osteoporosis or osteopenia using polymerase chain reaction-restriction fragment length polymorphism.

Fifteen and nine beta-thalassemia major patients displayed SS and Ss genotypes, respectively, whereas 13 were found to have an ss genotype. The mean BMD of the beta-thalassemia major patients with ss genotype was similar to those with the Ss and SS genotypes. In the control group, 77 and 15 subjects had SS and Ss genotypes, respectively, with no ss genotype. Allelic and genotypic distribution in patients were significantly different from controls.

Determining base substitutions at the Sp1 binding site on the COLIA1 gene in early years may be important in preventing osteoporosis in children with beta-thalassemia major.