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Derek J. Le, Ricardo F Frausto, Anthony J Aldave; Identification of Candidate Genes for a Corneal Dystrophy of Bowman Layer Not Associated with a TGFBI Mutation. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1012.
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To identify the genetic basis of a corneal dystrophy of Bowman layer (CDB) not associated with a TGFBI gene mutation using whole exome sequencing.
Slit-lamp examination was performed for affected members of a family with 7 individuals in 3 consecutive generations demonstrating Bowman layer opacities consistent with a CDB. Genomic DNA was isolated from peripheral blood of 2 affected and 1 unaffected individuals, and next-generation whole exome sequencing (WES) was performed. Heterozygous variants segregating with the affected phenotype were filtered against the SNP databases dbSNP137 and the 1000 Genomes Project. Variants identified in genes that did not show corneal expression were then filtered out, with the remaining variants validated by Sanger sequencing. The validated variants were then screened by Sanger sequencing in 2 additional affected individuals who did not undergo WES, and variants not present in both were filtered out. The predicted impact of the remaining missense variants on the function of the encoded protein was assessed using a variety of commonly used tools (PolyPhen2, SIFT, Provean, Condel, and MutationAssessor).
WES identified 27 novel heterozygous variants, each in a unique gene expressed in the cornea, in both affected individuals and not in the unaffected individual or in the SNP databases. Screening for these variants in the 2 additional affected family members who did not undergo WES revealed that 10 of the 27 variants were present in both individuals. Two of these variants, located in BAZ2A and PAPLN, were predicted to have deleterious effects on the encoded protein by ≥ 4 of the 6 prediction tools.
Using whole exome sequencing and corneal gene expression data, we have identified 10 candidate genes for a CDB not associated with a TGFBI gene mutation. Screening of these candidate genes in other reported families with CDB not related to a TGFBI gene mutation will likely lead to the identification of the genetic basis of the disorder in these families.
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