Three individuals in the CFS group were excluded from the analysis, one due to a B cell lymphocytosis (B cells represented 24% of lymphocytes showing a total B cell count of 435 cells/μL, with more than 85% of cells showing a IgD+IgM–CD23+CD27+CD5+CD38– phenotype), one due to an IgA deficiency and a third due to sample unavailability. This evidence concerns the gene CD27 and selective IgA deficiency disease.