DNA repair mechanisms in Chediak--Higashi syndrome cells

Chediak-Higashi syndrome in a black child

Chediak-Higashi syndrome (CHS) is an uncommon genetic disorder with a constellation of clinical, pathologic, and immunologic manifestations. It is rarely reported in blacks. Pathognomonic intracellular inclusions in white blood cells are well recognized; however, characteristic abnormal melanin aggregation into giant melanosomes also occurs, as can be readily seen by histologic evaluation of hair. We present a case of CHS in a black child.

Alterations of NAD and adenylyl dinucleotide metabolism in Chediak-Higashi syndrome fibroblasts

Chediak-Higashi syndrome (CHS) cells have been previously observed to exhibit several of the same characteristics as those of xeroderma pigmentosum (XP) and xeroderma pigmentosum variants. Cultured CHS fibroblasts have been examined for altered responses in both depletion of NAD and elevation of diadenosine-5',5"'-tetraphosphate (Ap4A) following DNA damage since both responses have been reported as altered in XP cells and since Ap4A has been reported as absent from the platelets of CHS patients. Lowering of NAD following UV irradiation occurred in CHS cells in a manner similar to that of control and XP variant cells, but different from that of XP cells. CHS fibroblasts were not found to be deficient in Ap4A and exhibit basal levels very similar to those of control fibroblasts. No change in Ap4A pools were observed which correlated with cell growth, in contrast to previously published reports. Furthermore, while Ap4A levels are not elevated in XP cells, we observe an elevation of Ap4A pools in CHS cells which mimics the elevations observed in control and XP variant cells. We conclude that: (1) CHS cells more closely resemble control or XP variant cells than XP cells with regard to NAD lowering and Ap4A elevation following UV irradiation; (2) the photosensitivity exhibited by CHS cells is not due to general defects in the synthesis of poly(ADP-ribose) from NAD or in Ap4A metabolism; and (3) alteration of Ap4A pool size in CHS fibroblasts is inappropriate as a biochemical marker for CHS.

The accelerated phase of Chediak-Higashi syndrome. An expression of the virus-associated hemophagocytic syndrome?

The clinical and pathologic findings of four patients with Chediak-Higashi syndrome in the accelerated phase were studied in order to clarify the nature of this enigmatic process. Fever, lymphadenopathy, hepatosplenomegaly, and cytopenias were present in every patient. All cases demonstrated extensive parenchymal infiltrates in many organs composed of benign-appearing histiocytes manifesting hemophagocytosis accompanied by lymphocytes and plasma cells. Studies in one patient suggested a viral etiology with the findings of a low blood lymphocyte OKT4 to OKT8 ratio, acquired loss of lymphocyte response to mitogens, the presence of Epstein-Barr virus genome in the mononuclear cells of lymph node, blood, and bone marrow, and possible clinical responses to acyclovir. It is concluded that the accelerated phase of Chediak-Higashi syndrome may be the clinicopathologic expression of the virus-associated hemophagocytic syndrome.