Background To describe mutations in the transforming growth factor-beta induced (TGFBI) gene in Asian patients with Bowman's membrane as well as stromal corneal dystrophies, and to elucidate their structural implications, using model peptides.
Methods Twenty-two unrelated Asian families were examined clinically including visual acuity testing and ocular examination with slit lamp biomicroscopy. Genomic DNA was extracted and the 17 exons of the TGFBI gene were amplified by PCR and sequenced bi-directionally. Biophysical techniques were used to characterise the wild type and mutant model peptides.
Results Molecular genetic analysis identified a variety of mutations in our patient series including a novel heterozygous C to A transversion mutation in exon 14 (c.1859C→A), resulting in a substitution of a highly conserved alanine residue by aspartic acid (p.A620D). Clinical presentation in the patient with the p.A620D included subepithelial scarring in addition to the linear branching opacities usually seen with lattice dystrophy. Using model peptides, we showed that A620D mutant peptide alters the secondary structure and conformational stability, and increased amyloid formation.
Conclusion A novel mutation (A620D) in transforming growth factor-beta induced protein (TGFβIp) is described, expanding the repertoire of mutations in this protein. Using model peptides, we demonstrated that A→D substitution leads to perturbation of the secondary structure that may be responsible for the amyloid formation in lattice corneal dystrophy.
- lattice corneal dystrophy
- conformational stability
- experimental and 8211 animal models
- treatment lasers
- clinical trial
- experimental and 8211 laboratory
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Competing interests None to declare.
Patient consent Obtained.
Ethics approval Institutional Review Board, Singapore National Eye Centre, Singapore. All parts of the study were performed according to the tenets of the Declaration of Helsinki.
Provenance and peer review Not commissioned; externally peer reviewed.