Comparison of two phenotypically distinct lattice corneal dystrophies caused by mutations in the transforming growth factor beta induced (TGFBI) gene

Proteomics Clin Appl. 2014 Apr;8(3-4):168-77. doi: 10.1002/prca.201300058. Epub 2014 Feb 16.


Purpose: In this study, we investigated whether the phenotypic difference observed between two lattice corneal dystrophy type 1 (LCD type 1) cases caused by either a single A546D substitution or an A546D/P551Q double substitution in TGFBIp (transforming growth factor beta induced protein) can be ascribed to (i) a difference in the proteomes of corneal amyloid deposits, (ii) altered proteolysis of TGFBIp, or (iii) structural changes of TGFBIp introduced by the P551Q amino acid substitution.

Experimental design: Amyloid deposits were isolated from the corneas of two siblings with LCD type 1 resulting from A546D/P551Q mutations in the TGFBI gene using laser capture microdissection and subsequently analyzed by LC-MS/MS. Proteolytic processing of TGFBIp was addressed by counting peptide spectra. Lastly, to study the possible effect of the P551Q substitution, recombinant FAS1-4 domain variants were subjected to in vitro stability assays.

Results: The amyloid proteomes and TGFBIp processing of the two A546D/P551Q LCD type 1 cases were similar to each other as well as to the A546D amyloid proteome previously reported by us. The stability assays revealed a minor destabilization of the FAS1-4 domain upon the addition of the P551Q mutation, moreover, it resulted in different accessibility to tryptic cleavage sites between the A546D and A546D/P551Q mutant FAS1-4 domain variants.

Conclusion and clinical relevance: The difference in A546D and A546D/P551Q LCD type 1 phenotypes cannot be ascribed to altered corneal amyloid composition or altered in vivo proteolytic processing of TGFBIp. Instead, a small difference in thermodynamic stability introduced by the P551Q mutation most likely causes structural changes of TGFBIp. The MS proteomics data have been deposited to the ProteomeXchange with identifier PXD000307 (

Keywords: Amyloid deposits; Cornea; Laser capture microdissection; Lattice corneal dystrophy; Paraffin-embedded tissue.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Substitution / genetics
  • Amyloid / metabolism
  • Chromatography, Liquid
  • Cornea / metabolism
  • Cornea / pathology*
  • Corneal Dystrophies, Hereditary / genetics*
  • Corneal Dystrophies, Hereditary / metabolism
  • Corneal Dystrophies, Hereditary / pathology
  • Extracellular Matrix Proteins / biosynthesis
  • Extracellular Matrix Proteins / chemistry
  • Extracellular Matrix Proteins / genetics*
  • Humans
  • Laser Capture Microdissection
  • Mutation
  • Proteolysis
  • Tandem Mass Spectrometry
  • Transforming Growth Factor beta / chemistry
  • Transforming Growth Factor beta / genetics*


  • Amyloid
  • Extracellular Matrix Proteins
  • Transforming Growth Factor beta
  • betaIG-H3 protein

Supplementary concepts

  • Lattice corneal dystrophy type 1