Objective: To report the case of two siblings with chronic granulomatous disease. Chronic granulomatous disease is a primary immunodeficiency disorder characterized by abnormal microbicidal activity. Mutations in the p47-phox gene (NCF-1) are present in about 30% of the patients with chronic granulomatous disease; this group presents a better prognosis and later onset of recurrent infections as compared with the X-linked variant, present in about 56% of patients. Description: Case 1 is a female presenting repeat infections since age 10, starting with impetigo followed by severe pneumonia six months later. The severity of the lung infection associated with liver abscess and the patient's resistance to treatment prompted laboratory investigation for immunodeficiency. The results of the nitroblue tetrazolium and superoxide release tests were consistent with a diagnosis of chronic granulomatous disease. The parents and siblings were assessed, revealing the presence of granulomatous disease in a brother (Case 2). He also presented repeat infections with impetigo at age 10, followed by pneumonia six months later, however in a non severe form. Single-strand conformational polymorphism analysis detected abnormal electrophoretic mobility of exon 2 of the NCF-1 gene. Sequence DNA analysis revealed a dinucleotide GT deletion in exon 2. Comments: It is important to evaluate the relatives of chronic granulomatous disease patients, even in the absence of typical clinical signs. Defining the mutation and its correlation with phenotype is important to provide appropriate genetic counseling and clinical prognosis. Copyright © 2004 by Sociedade Brasileira de Pediatria.805425428Curnutte, J.T., Chronic granulomatous disease: The solving of a clinical riddle at the molecular level (1993) Clin Immunol Immunopathol, 67 (3 PART 2), pp. S2-15Winkelstein, J.A., Marino, M.C., Johnston Jr., R.B., Boyle, J., Curnutte, J., Gallin, J.I., Chronic granulomatous disease. Report on a national registry of 368 patients (2000) Medicine, 79 (3), pp. 155-169. , BaltimoreLeusen, J.H., Verhoeven, A.J., Roos, D., Interactions between the components of the human NADPH oxidase: Intrigues in the phox family (1996) J Lab Clin Med, 128, pp. 461-476Renner, W.R., Johnson, J.F., Lichtenstein, J.E., Kirks, D.R., Esophageal inflammation and stricture: Complication of chronic granulomatous disease of childhood (1991) Radiology, 178, pp. 189-191Al-Binali, A.M., Scott, B., Al-Garni, A., Montgomery, M., Robertson, M., Granulomatous pulmonary disease in a child: An unusual presentation of Crohn's disease (2003) Pediatr Pulmonol, 36, pp. 76-80Liese, J., Kloos, S., Jendrossek, V., Petropoulou, T., Wintergerst, U., Notheis, G., Long-term follow-up and outcome of 39 patients with chronic granulomatous disease (2000) J Pediatr, 137, pp. 687-693Conley, M.E., Diagnostic guidelines - An International Consensus document (1999) Clin Immunol, 93, p. 189Ochs, H., Igo, R.P., The NBT slide test: A simple screening method for detecting chronic granulomatous disease and female carriers (1973) J Pediatr, 83, pp. 77-82Segal, B.H., Leto, T.L., Gallin, J.I., Malech, H.L., Holland, S.M., Genetic, biochemical, and clinical features of chronic granulomatous disease (2000) Medicine, 79, pp. 170-200. , BaltimoreBridges, R.A., Berendes, H., Good, R.A., A fatal granulomatous disease of childhood. The clinical, pathological and laboratory features of a new syndrome (1959) Am J Dis Child, 97, pp. 387-408Cross, A.R., Yarchover, J.L., Curnutte, J.T., The superoxide-generating system of human neutrophils possesses a novel diaphorase activity. Evidence for distinct regulation of electron flow within NADPH oxidase by p67-phox and p47-phox (1994) J Biol Chem, 269, pp. 21448-21454Andrade, C.C.P., (2003) Aspectos Clínicos de Pacientes Sob Suspeita de Imunodeficiência Fagocitária, , [dissertação]. Campinas: Universidade Estadual de CampinasHeyworth, P.G., Curnutte, J.T., Rae, J., Noack, D., Roos, D., Van Koppen, E., Hematologically important mutations: X-linked chronic granulomatous disease (second update) (2001) Blood Cells Mol Dis, 27, pp. 16-26Roesler, J., Curnutte, J.T., Rae, J., Barrett, D., Patino, P., Chanock, S.J., Recombination events between the p47-phox gene and its highly homologous pseudogenes are the main cause of autosomal recessive chronic granulomatous disease (2000) Blood, 95, pp. 2150-2156Vazquez, N., Lehrnbecher, T., Chen, R., Christensen, B.L., Gallin, J.I., Malech, H., Mutational analysis of patients with p47-phox-deficient chronic granulomatous disease: The significance of recombination events between the p47-phox gene (NCF1) and its highly homologous pseudogenes (2001) Exp Hematol, 29, pp. 234-243De Boer, M., Singh, V., Dekker, J., Di Rocco, M., Goldblatt, D., Roos, D., Prenatal diagnosis in two families with autosomal, p47(phox)-deficient chronic granulomatous disease due to a novel point mutation in NCF1 (2002) Prenat Diagn, 22, pp. 235-240