PIK3CD and infection: While T cell alterations are constant and recurrent in APDS-1 patients, perturbations in B cell phenotype and Ig serum levels do not appear equally constant and recurrent, suggesting that PIK3CD gene analysis may be undertaken in patients with recurrent infections, lymphoproliferation, and aberrant T-lymphocyte distribution with increased senescence and activation, even in the absence of hypogammaglobulinemia or CVID-like phenotype.