Foreword to the English Translation of Kostmann's Memoirs.

The defining feature of both discoveries was the concomitant occurrence of a rare infectious phenotype (i.e., recurrent, multiple bacterial infections), and a distinctive hematoimmunological phenotype (i.e., an endophenotype that was understood to underlie the clinical phenotype), displaying Mendelian inheritance (i.e., complete penetrance). The descriptions of boys with X-linked recessive agammaglobulinemia by Ogden Bruton in 1952 [[1]], and David Gitlin, Charles Janeway and their colleagues in 1953 [[3]-[5]] have long been held to constitute the birth of "primary immunodeficiencies." Coincidentally, Bruton and Kostmann were both pediatricians working for the military, Bruton in the USA and Kostmann in Sweden. It is not coincidental that Kostmann's and Bruton's diseases were designated by their hemato-immunological phenotypes, hereditary neutropenia and agammaglobulinemia, unlike Lutz' epidemodysplasia verrucifomis. [Extracted from the article]