Microarray–based mutation analysis of the genes underlying Leber congenital amaurosis reveals the CRB1 gene as the most frequent cause of LCA

Abstract

Abstract: : Purpose: To identify mutations in a cohort of unrelated Dutch and Belgian LCA patients and to perform a genotype–phenotype analysis. Methods:Twenty–nine patients with LCA were ascertained from the Netherlands and Belgium. DNA was extracted from peripheral blood and analyzed using a LCA microarray chip containing 258 disease associated sequence variants previously identified in 8 LCA or early–onset RP genes (AIPL1, CRB1, CRX, GUCY2D, LRAT, MERTK, RPE65, and RPGRIP1). Mutations were confirmed by sequencing and, if possible segregation analyses was performed. When one mutation was found, the relevant gene was fully sequenced. Patients were ophthalmologically analysed. Results: Heterozygous sequence variants were found in GUCY2D (three patients), AIPL1 (two patients) and CRB1 (one patient). Three patients carried two mutations in CRB1 and two patients carried homozygous GUCY2D sequence variants. One patient showed two CRB1 mutations as well as one sequence variant in AIPL1. Segregation analysis of mutations is ongoing. Conclusions:Microarray–based mutation analysis revealed known sequence variants in 12 of 29 LCA patients. All sequence variants diagnosed with chip–analyses could be confirmed by DNA sequencing. In five of the 12 patients pathologic mutations in the CRB1 gene were involved. The microarray analysis represents a fast and relatively cheap diagnostic tool. In patients with one mutation sequence analysis readily identifies novel LCA mutations which subsequently can be added to the chip to enhance its efficacy.

Keywords: retinal degenerations: hereditary • gene microarray • mutations