Table 1. Frequencies of type 1 diabetes in siblings of diabetic probands in Caucasian and Japanese populations.

^Legenda Data from Risch [13]. ^b Data from Karvonen et al. [14] and Ikegami et al. [15]. ^c Data from Ikegami et al. [15]. ^d Based on a survey of family history of type 1 diabetes at summer camps for childhood diabetes in 1998 [16]. ^e Based on data from the Committee on Immunogenetics of Type 1 Diabetes of the Japan Diabetes Society, 1987. The frequency was calculated from the number of patients with type 1 diabetes in siblings of type 1 diabetic probands divided by the number of families studied, because of a lack of information on the number of siblings in each family. Based on the average number of children (approximately 2) in each family in Japan in 1987, the frequency may not have been overestimated as compared with the frequency calculated from the number of patients divided by the number of siblings.