Abstract
Purpose: :
Autosomal Recessive Retinitis Pigmentosa (AR-RP) displays high degree of genetic and clinical heterogeneity. The mutations spectrum associated with the disease can vary significantly among different ethnic groups; we report on a molecular analysis of Italian AR-RP patients, performed by means of microarray technology.
Methods: :
Seventy-eight AR-RP patients originating from different part of Italy were included in the study. Diagnostic criteria were: early onset retinal dystrophy with typical pigment clumping, electroretinogram (ERG) severe abnormalities, visual field concentric restriction. All the patients underwent a standard ophthalmic examination, including fundoscopy, ERG (Retimax, Roland Consult, Brandenburg, Germany) and Humphrey computerized perimetry (Zeiss, Dublin, CA, USA). Mutation analysis was performed by means of a microarray chip APEX (Arrayed Primer Extension), including the most frequent mutations associated with AR-RP (501 mutations in 16 genes) (Asper Biotech, , Tartu, Estonia ). In the cases where the microarray screening detected only one mutation, the whole gene was sequenced. The samples of the patients where the chip could not identify any mutation were analysed for ABCA4 gene sequence variants by means of an automated sequencing system (3730 DNA Analyzer, Applied Biosystems, Foster City KA, USA).
Results: :
Twelve sequence variants (in the genes CRB1, USH2A, PDE6A, CERKL, CNGA1, RGR, RDH12, RPE65, MERTK) were identified by means of the microarray technology and other 6 mutations could be detected by sequencing. Five ABCA4 mutations were identified in 4 patients. Altogether the protocol allowed the identification of 23 sequence variants out of 26/78 AP-RP patients (33 %). USH2A was the most frequently mutated gene.
Conclusions: :
In AR-RP microarray technology may represent a relatively cheap and fast method for mutation analysis, providing useful information for prognostic evaluation and patients recruitment in future trials of gene therapy.
Keywords: retinal degenerations: hereditary • gene microarray • mutations