In a patient with X-linked CGD (306400) first reported by Ezekowitz et al. (1988), Rae et al. (1998) identified a T-to-C change in the 5-prime splice site of intron 1 of the CYBB gene, resulting in a diminished level of p91-phox. In this patient, Ezekowitz et al. (1988) found that interferon-gamma (IFNG; 147570), an activator of phagocytes, resulted in a 5- to 10-fold increase in superoxide production by granulocytes and monocytes, a proportionate rise in granulocyte bactericidal activity, and an increase in the cellular contents of phagocyte cytochrome b and immunoreactive cytochrome b heavy chain. In other CGD group studies, however, no apparent increases in phagocyte superoxide generation were observed. For that reason, the patient studied by Ezekowitz et al. (1988) was considered to be an exceptional case. Condino-Neto and Newburger (2000) proposed that IFN-gamma improved the splicing efficiency of CYBB gene transcripts in that patient and corrected a nuclear processing defect due to the intronic mutation by augmenting nuclear export of normal transcripts.
