Heritability of IgA, IgG and IgM levels was studied in 85 MZ and DZ twin pairs of both sexes. Immunoglobulin concentrations were determined by single radial diffusion. Significantly higher geometric mean of IgM level in females than males was demonstrated. Heritability coefficients h2, F and VG/VE were higher in male than female twins. This suggests that genetic factors play a more important role in males as compared with females in regulating the three immunoglobulin levels. Quantitative comparison of genetic variances of both sexes indicated slightly greater genetic influence in the case of IgA in females. Environmental variances of IgA and IgM levels were also higher in females than males.

Four groups of children were tested for the distribution of C3 and BF phenotypes: HBV-infected patients with Gianotti-Crosti syndrome, with CAH and with glomerulonephritis, and healthy children. The frequency of the phenotype C3F was significantly higher in children with Gianotti-Crosti syndrome in comparison with healthy children. The frequency of the phenotype BFS was significantly higher in patients with glomerulonephritis than in individuals with CAH. The difference between the frequency of the BFS phenotype in glomerulonephritis patients and that in healthy subjects neared significance. We suggest that the carriers of these phenotypes are characterized by susceptibility to some immune complex diseases associated with HBV infection.

Patients with CAH, extrahepatic HBV manifestation and healthy children were studied for presence of Gm 1, 2, 3, 10, 21 factors and Km 1 factor. significantly higher frequency of Gm (1, 2, 3, 10, 21) phenotype was shown in CAH group as compared with the other two groups. Relationship between Km factors and examined groups was not found.

Heritabilities of antibody levels to measles, rubella, and mumps were estimated in 88 MZ and DZ twin pairs. The contribution of genetic factors in phenotypic antibody levels to measles was somewhat lower than environmental factors in both sexes (h = 0.450 and 0.459). A significantly stronger genetic than environmental control of anti-mumps antibody levels was evident in both sexes, but more so in females (h = 0.882) than in males (h = 0.626). The genetic determination of anti-rubella antibodies was also significantly higher in girls (h = 0.833), while environmental determination was greater in boys (h = 0.350). © 1995 Wiley-Liss, Inc.

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