COL1A1 SP1 binding site polymorphism is associated with otosclerosis in two independent populations

Otosclerosis is one of the most common causes of acquired hearing loss. Although the etiology of otosclerosis is unknown, there is a well established genetic predisposition. One of the most important candidate genes is the collagen type I-a1 gene [COL1A1]. A single nucleotide polymorphism affecting a binding site for the transcription factor Sp1 in COL1A1 has been associated with an increased risk of otosclerosis. To verify the possible association between the polymorphism of the Sp1 binding site of COL1A1 and otosclerosis. Polymerase chain reaction followed by restriction enzyme digestion was used to determine the polymorphic distribution of the COL1A1 Sp1 binding site in patients with otosclerosis and in control subjects. In the first part of the study, we enrolled 89 Egyptian otosclerotic patients and 89 healthy control subjects. The second part was conducted in Switzerland, on 52 patients with otosclerosis and 52 controls. The Sp1 allelic frequencies in the Egyptian and Swiss populations were very similar. The T allele frequencies were 0.36 and 0.33 in patients from Egypt and Switzerland, respectively. However, among the controls, the frequency was 0.14 in the Egyptians and 0.13 in the Swiss subjects. This study showed a significant association between otoscierosis and the T allele in the Egyptian population [p< 0.0001]. Analysis of the independent Swiss population replicated this association [p= 0.0005]. The study confirms the association of COL1A1 Sp1 binding site polymorphism with the risk of otosclerosis