The 5 G/5 G genotype of PAI-1 polymorphism is linked to decreased plasminogen activator inhibitor-1 (PAI-1) levels and it has been suggested that lower PAI-1 levels may provide protective effects on inflammation, local microcirculatory disturbance, and fibrotic changes, which are likely associated with development of sudden sensorineural hearing loss (SSNHL).
The association of the 4G/5G PAI-1 polymorphism with the development and clinical outcome of SSNHL is evaluated via a case control study. 103 patients with SSNHL and 113 age and sex-matched controls were enrolled at University of Ferrara, Italy and hearing loss outcome was measured at least 3months after the onset of hearing loss. DNA was isolated from peripheral blood using the QIAamp kit and the 4G/5G polymorphism in the −675 promoter region was genotyped with an allele-specific PCR. Genotype distribution was tested in patients and compared to controls by chi-square and odd-ratio analysis. The codominant and recessive models were used for the multiple logistic regression analyses of the PAI-1 gene allele.
In this population, 5G/5G genotype had a two-time lower frequency in SSNHL patients compared to healthy controls (15.5% vs 30.1%) and was associated with decreased odds compared to 4G/5G genotype (OR 0.37, 95% CI 0.19-0.75, p=0.005). In addition, the patients with 5G/5G genotype showed a trend of more than 2 times higher ratio of hearing recovery (> 20dB) after systemic corticosteroid treatment compared to 4G/5G genotype (OR 2.3, 95% CI 0.32 - 16.83, p=0.39), suggesting a better clinical outcome.
The 5G/5G genotype of PAI-1 may be associated with a reduced risk of SSNHL in the Italian population.
Keywords: Sudden hearing loss, Plasminogen activator inhibitor-1, 4G/5G polymorphism