Figure 1. Diagram explaining the selection of patients for this study. Initially, 101 non-related patients, 13 diagnosed with retinitis
pigmentosa (RP) and 88 diagnosed with Usher syndrome (USH) were screened for point mutations in USH2A by Sanger sequencing. Point mutations in both USH2A alleles were identified in 42 of them. Later one, seven USH patients were found to carry mutations in DFNB31. After all these previous studies, 13 USH DNA samples were degraded and only 39 samples were useful to perform the MLPA analysis
to search for large deletions/duplications in the USH2A gene. Finally, an additional DNA sample from a patient carrying a homozygous USH2A deletion involving exons 9-14 was included in the study as a positive control for the MLPA analysis.