Partial C4 deficiency in subacute sclerosing panencephalitis.

In an immunogenetic study, 23 subacute sclerosing panencephalitis (SSPE) patients and their families were studied for the HLA region markers HLA-A, B, C, DR, BF, C2, C4A, C4B, GLO I, and PGM3. In addition, C3, C4, and factor B serum levels were determined. A highly significant association of C4A QO with SSPE was found. Furthermore, two rare haplotypes, C4A QOB QO, two C4ACh+ allotypes, and four Ch partial inhibitors were detected, which possibly impair the function of the C4 molecules. HLA-DR5 was increased. In addition, a number of rare HLA-A, C, B, DR haplotypes were observed. It is postulated that rare C4 molecular deficiency might be a predisposing factor in the pathogenesis of SSPE.