x-linked agammaglobulinemia (xla) is an immunodeficiency caused by mutations in the bruton tyrosine kinase (btk) gene. in order to identify the mutations in btk gene in iranian patients with antibody deficiency, 13 male patients with an xla phenotype from 11 unrelated families were enrolled as the subjects of investigation for btk mutation analysis using pcr-sscp followed by sequencing. five di...