Occasionally one picks up hypogammaglobulinaemia unexpectedly in a young person. Most of them look well and give no history of serious infections. Some will have lymphangiectasia, but most will have a protein losing enteropathy due to malabsorption, caused by either Crohn's disease or coeliac disease.
An important clue in such cases is low IgG and IgA, in combination with a raised IgM. As far as I know, this does not happen in any other form of severe hypogammaglobulinaemia.
