HYPOCOMPLEMENTEMIA DUE TO A GENETIC DEFICIENCY OF BETA-1H GLOBULIN

Abstract

An 8-mo. old Asian boy who presented with the hemolytic uremic syndrome had a low hemolytic complement (C), and in particular a very low C3 level, with normal C4 level. These abnormalities persisted after recovery and were not associated with the presence of circulating C3 nephritic factor. A clinically healthy 3-yr-old brother had an identical C profile, indicating increased alternative pathway activation. Both brothers had normal levels of the C3b inactivator, but very low levels of .beta.1H globulin (< 40% of a reference standard serum). The parents, who were 1st cousins, had half-normal levels of .beta.1H globulin, and low levels were found in other members of the family, indicating that the defect was inherited.