The identification of many genes responsible for primary immunodeficiencies has provided
us with a new perspective to evaluate these disorders. It has clarified the clinical and
laboratory findings that are most consistently associated with a specific gene, demonstrated
the spectrum of clinical severity seen in a particular disorder, and shown that not all of the
patients with identical clinical and laboratory findings have mutations in the same gene. This
new information allows us to reevaluate the criteria that we use to make diagnoses. The …