Missense mutations in the gp91-phox gene encoding cytochrome b(558) in patients with cytochrome b positive and negative X-linked chronic granulomatous disease

Chronic granulomatous disease (CGD) is a disorder of host defense due to ge netic defects of the superoxide (O-2(-)) generating NADPH oxidase in phagoc ytes, A membrane-bound cytochrome b(558), a heterodimer consisting of gp91- phox and p22-phox, is a critical component of the oxidase. The X-linked for m of the disease is due to defects in the gp91-phox gene. We report here bi ochemical and genetic analyses of patients with typical and atypical X-link ed CGD. Immunoblots showed that neutrophils from one patient had small amou nts of p22-phox and gp91-phox and a low level of O-2(-) forming oxidase act ivity, in contrast to the complete absence of both subunits in two patients with typical CGD. Using polymerase chain reactions (PCR) on cDNA and genom ic DNA, we found novel missense mutations of gp91-phox in the two typical p atients and a point mutation in the variant CGD, a characteristic common to two other patients with similar variant CGD reported previously. Spectroph otometric analysis of the neutrophils from the variant patient provided evi dence for the presence of heme of cytochrome b(558) Recently, we reported a nother variant CGD with similar amounts of both subunits, hut without oxida se activity or the heme spectrum. A predicted mutation at amino acid 101 in gp91-phox was also confirmed in this variant CGD by PCR of the genomic DNA . These results on four patients, including those with two variant CGD, are discussed with respect to the missense mutated sites and the heme binding ligands in gp91-phox. (C) 1999 by The American Society of Hematology.