Haemophagocytic lymphohistiocytosis in X-linked severe combined immunodeficiency

Haemophagocytic lymphohistiocytosis (HLH) is characterized by destruction o f haematopoietic elements, and is associated with a variety of manifestatio ns including immune abnormalities. We describe an infant with HLH who had n o evidence of infection or malignancy, He had markedly reduced natural kill er (NK) and T-cell numbers and mitogen responses, consistent with severe co mbined immune deficiency, Western blot and now cytometry analyses revealed an absence of interleukin (IL)-2 receptor gamma (gamma common) chain expres sion and a transition (C --> T) at nucleotide 684 in the gamma common gene. This novel case highlights the need for a thorough evaluation of immunolog ical phenotype and genotype in patients with HLH.