Distribution of certain autoantibodies in monozygotic and dizygotic twins.

It is now well established that autoantibodies are found in a number of disease conditions such as Hashimoto's disease and primary hypothyroidism (Roitt and Doniach, 1958, 1960; Buchanan and Harden, 1965), pernicious anaemia (Doniach, Roitt, and Taylor, 1963; Irvine, 1965), and some connective tissue diseases, notably rheumatoid arthritis (Vaughan, 1959; Singer, 1961; Christian, 1963) and systemic lupus erythematosus (Holman, 1960; Shulman, 1963), but the significance of the autoantibodies in these diseases is unknown. Several groups of workers have reported familial aggregation of serum autoantibodies in Hashimoto's disease (Hall, Owen, and Smart, 1960; Hall, DeGroot, McDermott, and Davis, 1962), pernicious anaemia (Doniach, Roitt, and Taylor, 1965), rheumatoid arthritis (Lawrence and Ball, 1958; Ziff, Schmidt, Lewis, and Tanner, 1958; Bremner, Alexander, and Duthie, 1959; Robecchi and Daneo, 1959; Lawrence, Laine, and de Graaff, 1961), and systemic lupus erythematosus (Brunjes, Zike, and Julian, 1961; Siegal, Lee, Widelock, Reilly, Wise, Zingale, and Fuerst, 1962; Leonhardt, 1964). However, it is not known whether this familial aggregation is genetically or environmentally determined. Furthermore, Bunim and his colleagues (Bunim, Burch, and O'Brien, 1964; Burch, O'Brien, and Bunim, 1964), in a careful epidemiological study of the North American Indians, failed to find familial aggregation of rheumatoid factor. Autoantibodies found in the diseases mentioned above exist in low titre in some normal individuals (Goudie, Anderson, and Gray, 1959; Alexander, Bremner, and Duthie, 1960; Hackett, Beech, and Forbes, 1960; Ball and Lawrence, 1961; Hill, 1961; Buchanan, Harden, Koutras, and Gray, 1965). We therefore thought it of interest to contrast the concordance rates of autoantibodies in monozygotic and dizygotic healthy twins in an attempt to evaluate the relative role of genetic and environmental factors in autoantibody production. The autoantibodies studied include autoantibodies to thyroid "microsomes" and thyroglobulin, autoantibodies to the cytoplasm of the gastric parietal cell, rheumatoid factor, and antinuclear autoantibody (antinuclear factor).