ABSTRACT
Immunodeficiencies are classified as either primary diseases with a genetic origin or diseases that are secondary to an underlying disorder.
X-linked (congenital) agammaglobulinemia
results from a failure of pre-B cells to differentiate into mature B cells. The defect in
Bruton’s disease
is in the rearrangement of immunoglobulin heavychain genes. This disorder occurs almost entirely in males and is apparent after 6 months of age, following the disappearance of the passively transferred maternal immunoglobulins. Patients have recurrent sinopulmonary infections caused by
Haemophilus influenzae, Streptococcus pyogenes, Staphlococcus aureus
, and
Streptococcus pneumoniae
, with absent or decreased B cells and decreased serum levels of all immunoglobulin classes. The T cell system and cell-mediated immunity appear normal.
