Molecular analysis of 14 Omani CGD patients from 10 families, diagnosed to have CGD on clinical (recurrent infections) and biochemical grounds (positive for both the nitroblue tetrazolium (NBT) test and the dihydrorhodamine (DHR-1,2,3 assay), revealed that only one patient had X-linked CGD, with a large deletion involving both the gp91-phox gene (CYBB) and the McLeod gene (XK).