CONCORDANCE FOR HODGKINS-DISEASE IN IDENTICAL-TWINS SUGGESTING GENETIC SUSCEPTIBILITY TO THE YOUNG-ADULT FORM OF THE DISEASE

Background. Relatives of young adults with Hodgkin's disease are at in creased risk of Hodgkin's disease, and lines of evidence implicate bot h inheritance and environment. Methods. We have identified and followe d 432 sets of twins affected by Hodgkin's disease. The number of cases of Hodgkin's disease observed before the age of 50 years in the healt hy monozygotic and dizygotic twins of the patients with Hodgkin's dise ase was compared with the number expected from national age-specific i ncidence rates. Results. None of the 187 pairs of dizygotic twins beca me concordant for Hodgkin's disease, whereas 10 of the 179 pairs of mo nozygotic twins did; in 5 of these pairs, the second case appeared aft er the original ascertainment. During the observation period, 0.1 (mon ozygotic) and 0.1 (dizygotic) cases in the unaffected twins were expec ted. Monozygotic twins of patients with Hodgkin's disease thus had a g reatly increased risk (standardized incidence ratio, 99; 95 percent co nfidence interval, 48 to 182), whereas no increase in the risk for diz ygotic twins of patients with Hodgkin's disease was observed. Conclusi ons. Genetic susceptibility underlies Hodgkin's disease in young adult hood.