In other primary immunodeficiency disorders, such molecular chimerism has been linked to atypical and relatively milder disease courses, including ADA-deficient SCID [28, 29], X-linked ectodermal dysplasia and immunodeficiency [47], γc deficiency [30, 31] or Wiskott-Aldrich syndrome [24–27]. This evidence concerns the gene ADA and severe combined immunodeficiency.