Localization of deletions in the CYBB gene of the two patients. The shaded area indicates the deletions, comprising a 3.5-kb nucleotide stretch from intron 5 to intron 7 in patient 1 (the eldest brother) and a 3.0-kb nucleotide stretch from intron 4 to intron 5 in patient 2 (the youngest brother). The deletions overlap for 35 bp.