1. Two siblings with the Chediák-Higashi syndrome are reported. One, a three-year-old boy, died with malignant lymphoma; the other, a six-year-old girl, is alive and well.
2. Results of studies of white blood cell function and antibody production were normal, indicating that the increased susceptibility to infection of some Chediák-Higashi syndrome patients is probably not attributable to abnormal leukocytes or to deficient antibody production.
3. Results of investigations of some aspects of tryptophan metabolism indicated an interesting, unique, and as yet unexplained absence of 5-hydroxytryptamine in the peripheral blood.
4. A review of the reported cases of Chediák-Higashi syndrome indicates that these patients have a striking predisposition to a peculiar type of malignant lymphoma.
5. An unusual perivascular infiltrate of histiocytes has been noted in postmortem sections of brain of patients with this anomaly. It is not clear whether this is a manifestation of the malignant lymphoma or a reflection of the basic disease process.