Verity Oliver, David Markie, Phil Crosier3David Mackey, Trevor Sherwin, Charles McGhee,,Andrea Vincent
To identify the underlying genetic cause ofautosomal dominant recurrent corneal erosion dystro-phy in a NZ family, and characterise the diseasemechanism utilising zebrafish.
Twenty members of a 3-generation NZfamily were clinically examined and DNA samples col-lected. Candidate corneal dystrophy genes wereexcluded as published previously. Genome-wide scan-ning using a SNP microarray and subsequent exomesequencing of two affected individuals was undertaken.Bioinformatic analysis, protein prediction, and splicesite software were used to identify putative pathogenicvariants within the linkage region. Known genetic vari-ants were excluded using public databases of humanvariation, and changes validated with Sanger sequenc-ing. 14 family members from a clinically similar Tasma-nian family underwent Sanger sequencing. Expressionanalysis in human cornea using immunohisto-chemistry and RT-PCR, and in zebrafish using whole-mount in situ hybridisation is underway.
A genome-wide scan of the NZ family iden-tified one significant peak, reaching the maximumLOD possible (2.7) on chromosome 10. Exomesequencing and bioinformatics processing identifiedcandidate variants in three genes (COL17A1, DNAJC9and FRMPD2) in this region. Segregation was con-firmed for COL17A1 (G>A, new splice donor siteleading to deletion of 18 amino acids) and DNAJC9(C>T, substitution D112N) in the NZ family. TheCOL17A1 variant also segregated in the Tasmanianfamily. Preliminary data supports of COL17A1 expres-sion in human and zebrafish corneas.
The COL17A1 splice variant causing dele-tion of 18 amino acids is likely to be the causative muta-tion in our recurrent corneal erosion families. Azebrafish model of this dystrophy is being developed.