Another primary immunodeficiency disorder (PID), X-linked agammaglobulinemia (XLA), commonly caused by a mutation or deletion in the BTK gene which prevents the normal development of B lymphocytes and that results in a severe antibody deficiency, is being considered as a condition to be added into NBS panels in several countries [11,12,13]. This evidence concerns the gene BTK and Bruton-type agammaglobulinemia.