Southern blot RFLP assay of genomic DNA after digestion with EcoRI. (A) Shows the EcoRI restriction map of the CYBB gene. Hybridization was performed with a ³²P-labeled pSV-CGD cDNA probe, containing the entire coding region of CYBB. The length of the expected restriction fragments is indicated. (B) Shows the results with the DNA from a healthy control donor (lane C), from the mother of the patients (lane M), from the eldest patient (lane 1), and from the youngest patient (lane 2). The size of the indicated fragments was determined relative to HindIII digested phage-lambda DNA as size markers. Arrows at right point at differences between lane C and the other lanes.