Polymorphism of the fourth component of complement (C4) and three clinical pictures of hepatitis B virus infection in children.
The fourth component of complement (C4) phenotype and allele frequencies were studied in 3 groups of unrelated children affected with hepatitis B virus (HBV) infection (25 with glomerulonephritis (GN), 39 with chronic active hepatitis (CAH), 24 with Gianotti-Crosti syndrome (GS-S)) and in 100 unrelated healthy individuals (H). Ten phenotypes in GN, 14 in CAH, 10 in GC-S and 23 in H were found. Some rare phenotypes appeared in the individual cases of ill children. Statistical analysis was performed by chi-square test. Each group was compared to the others. We found significantly higher frequency of the A3B2,Q0 phenotype in CAH than in H as well as significant increase of the A x 4 gene frequency in GC-S as compared to H. However, these events could be caused by limited number of tested patients. We suspect that the association between C4 alleles and immune-complex diseases, studied here, does not rather exist.