Publications of Z Szekelyhidi

Genetic covariance between central corneal thickness and anterior chamber volume: a Hungarian twin study

Background: Few, and inconsistent, studies have showed high heritability of some parameters of the anterior segment of the eye; however, no heritability of anterior chamber volume (ACV) has been reported, and no study has been performed to investigate the correlation between the ACV and central corneal thickness (CCT). Methods: Anterior segment measurements (Pentacam, Oculus) were obtained from 220 eyes of 110 adult Hungarian twins (41 monozygotic and 14 same-sex dizygotic pairs; 80% women; age 48.6 ± 15.5 years) obtained from the Hungarian Twin Registry. Results: Age- and sex-adjusted heritability of ACV was 85% (bootstrapped 95% confidence interval; CI: 69% to 93%), and 88% for CCT (CI: 79% to 95%). Common environmental effects had no influence, and unshared environmental factors were responsible for 12% and 15% of the variance, respectively. The correlation between ACV and CCT was negative and significant (rph = −0.35, p < .05), and genetic factors accounted for the covariance significantly (0.934; CI: 0.418, 1.061) based on the bivariate Cholesky decomposition model. Conclusion: These findings support the high heritability of ACV and central corneal thickness, and a strong genetic covariance between them, which underscores the importance of identification of the specific genetic factors and the family risk-based screening of disorders related to these variables, such as open-angle and also angle closure glaucoma and corneal endothelial alterations.

Genetic effects on refraction and correlation with hemodynamic variables: a twin study

Spherical equivalent (SE) has not been linked to increased cardiovascular morbidity. Methods: 132 Hungarian twins (age 43.3±16.9 years) underwent refraction measurements (Huvitz MRK-3100 Premium AutoRefractokeratometer) and oscillometry (TensioMed Arteriograph). Results: Heritability analysis indicated major role for genetic components in the presence of right and left SE (82.7%, 95%CI, 62.9 to 93.7%, and 89.3%, 95%CI, 72.8 to 96.6%), while unshared environmental effects accounted for 17% (95%CI, 6.3% to 37%), and 11% (95%CI, 3.4% to 26.7%) of variations adjusted for age and sex. Bilateral SE showed weak age-dependent correlations with augmentation index (AIx), aortic pulse wave velocity (r ranging between 0.218 and 0.389, all p < 0.01), aortic systolic blood pressure and pulse pressure (r between 0.188 and 0.289, p < 0.05). Conclusions: These findings support heritability of spherical equivalent, which does not coexist with altered hemodynamics (e.g. accelerated arterial aging). Accordingly, SE and the investigated hemodynamic parameters seem neither phenotypically nor genetically associated. Keywords: arterial stiffness, augmentation index, genetics, heritability, refraction