Quantification of gene deletion by a SYBR-Green I assay. A. Pedigree of an ADOA family with a deletion of the entire OPA1 gene. Carriers of the deletion are indicated with filled symbols and normal individuals with open symbols . B. Real-time plot obtained for the quantification of the OPA1 gene deletion. Genomic DNA from 2 individuals (a carrier and a normal) was assayed for copy number of the OPA1 gene using the SYBR-Green I real-time PCR assay. Real-time OPA1 amplification plots for carriers (right panel) are consistently at least one cycle behind the plots obtained with GAPDH, while plots for GAPDH and OPA1 in non-carriers are almost superimposed (left panel). C. Quantification of the OPA1 gene deletion in 13 members of the family. DNA was extracted from family members indicated by letters on A. The OPA1 versus GAPDH PCR assay was performed. Non-carriers showed a ratio close to 1 for the GAPDH versus OPA1 quantification. In contrast, all carriers of the deletion showed a clear reduction in this ratio.