Association of otosclerosis with Sp1 binding site polymorphism in COL1A1 gene: Evidence for a shared genetic etiology with osteoporosis

Hypothesis: There is an association between otosclerosis and osteoporosis. Background: Both osteoporosis and otosclerosis are common bone diseases to which relatively large portions of the population are genetically predisposed. Recently, a strong association has been described between osteoporosis and an Sp1 binding site of putative functional significance in the first intron of the COLIA1 gene. Methods: We applied polymerase chain reaction-based restriction enzyme analysis to determine the polymorphic distribution of the Sp1 site in 100 patients with otosclerosis and 108 control subjects. Results: This study showed a significant association between otosclerosis and the COLIA1 first intron Sp1 site. The allelic frequency of the Sp1 site is very similar between otosclerosis and osteoporosis. Conclusion: Some cases of otosclerosis and osteoporosis could share a functionally significant polymorphism in the Sp1 transcription factor binding site in the first intron of the COLIA1 gene.