Combined immunodeficiency due to TFRC deficiency

A rare genetic combined T and B cell immunodeficiency characterized by life-threatening infections due to disrupted transferrin receptor 1 endocytosis, resulting in defective cellular iron transport and impaired T and B cell function. Patients present with early-onset chronic diarrhea, severe recurrent infections, and failure to thrive. Laboratory studies reveal hypo- or agammaglobulinemia, normal lymphocyte counts but decreased numbers of memory B cells, intermittent neutropenia and thrombocytopenia, and mild anemia (resistant to iron supplementation) with low mean corpuscular volume.