Van Zelm et al. (2006) evaluated 4 patients from 2 unrelated families who had increased susceptibility to infection, hypogammaglobulinemia, and normal numbers of mature B cells in blood, indicating a B-cell antibody-deficient immunodeficiency disorder. The disorder was consistent ... Van Zelm et al. (2006) evaluated 4 patients from 2 unrelated families who had increased susceptibility to infection, hypogammaglobulinemia, and normal numbers of mature B cells in blood, indicating a B-cell antibody-deficient immunodeficiency disorder. The disorder was consistent with a clinical diagnosis of common variable immunodeficiency syndrome. One family included 3 Colombian sibs examined at 35, 33, and 49 years of age, respectively. All 3 sibs had had otitis media, sinusitis, and pharyngitis during childhood. In addition, 1 had had 4 bouts of pneumonia between the ages of 18 and 35 years; he had received diagnoses of bacterial conjunctivitis and chronic gastritis (Helicobacter pylori infection). The proband of the other family was a Turkish girl, born of consanguineous parents, with a history of recurrent bronchiolitis and bronchopneumonia starting at 1 year of age and meningitis starting at 8 years of age. A diagnosis of postinfectious glomerulonephritis was made at the age of 10 years, at which time she was found to have hypogammaglobulinemia.
In 4 patients with common variable immunodeficiency, van Zelm et al. (2006) identified homozygous mutations in the CD19 gene. Levels of CD19 were undetectable in 1 patient and substantially reduced in the other 3. Based on laboratory studies, ... In 4 patients with common variable immunodeficiency, van Zelm et al. (2006) identified homozygous mutations in the CD19 gene. Levels of CD19 were undetectable in 1 patient and substantially reduced in the other 3. Based on laboratory studies, van Zelm et al. (2006) concluded that mutation of the CD19 gene causes a type of hypogammaglobulinemia in which the response of mature B cells to antigenic stimulation is defective. On the basis of the crucial role of CD19 in signaling by the B-cell receptor on antigen recognition, van Zelm et al. (2006) thought it likely that defects in other members of the CD19 complex (CD21, CD81, and CD225) may also lead to antibody deficiency in humans.