Absence of significant genetic alterations in the VSX1, SOD1, TIMP3, and LOX genes in Brazilian patients with Keratoconus

ABSTRACT

Purpose

To identify inherited or acquired mutations in the VSX1, SOD1, TIMP3 and LOX genes from the combined analysis of corneal and blood samples from patients with Keratoconus.

Methods

The casuistry was consisted of samples of peripheral blood and corneal epithelium from 35 unrelated patients with Keratoconus who were submitted to corneal crosslink treatment. Also, blood and corneal epithelium samples from 89 non-keratoconic patients were used to compose the control group. Ophthalmologic evaluations included a clinical examination, topography and tomography. DNA samples were extracted from peripheral blood and from corneal epithelium in both groups and all coding regions of the VSX1, SOD1, TIMP3 and LOX genes were amplified by polymerase chain reaction, denatured and subjected to polyacrylamide gel electrophoresis. Mutational screening was performed by single-strand conformation polymorphism and direct DNA sequencing.

Results

No pathogenic variant was found in all coding regions of VSX1, SOD1, TIMP3 and LOX genes, we detected only few SNPs (single-nucleotide polymorphisms). Among the polymorphisms stand out three of them, corresponding to the synonymous exchange of amino acids: exon 3 of VSX1 Ala182Ala and exon 3 of TIMP3 His83His and Ser87Ser; in patients with Keratoconus and also in control subjects. All the polymorphisms were found in samples of corneal epithelium and corresponding blood.

Conclusion

There is absence of KC pathogenic related to mutations in the VSX1, SOD1, TIMP3 and LOX genes in the studied patients.

KEYWORDS:

• Cornea
• Keratoconus
• ectasia
• genetic polymorphisms
• visual system homeobox 1 gene
• superoxide dismutase 1 gene
• lysyl oxidase gene
• TIMP3 gene

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author Contributions

Conceived and designed the experiments: AGL, GCAJr, LC. Performed the experiments: AGL, RMT, FCBLP and RAM. Performed the inclusion of patients, sample collection, and developed the clinical evaluation and clinical analyses: GCAJr. Analyzed the data: AGL, MPM, LCM, CCBM and LC. Wrote the paper: AGL, GCAJr, LCM and LC. All authors approved the manuscript.

Additional information

Funding

This study was supported by grants from Brazilian Ministry of Education – CAPES PhD Scholarship (Coordination of Improvement of Higher Education Personnel, Brazil); by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP grant number: 2015/17226-7 to GCAJr; 2017/09540-9 to FCBLP). The opinions, assumptions, and conclusions or recommendations expressed in this material are the responsibility of the authors and do not necessarily reflect the views of FAPESP. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.