The Breast Cancer Family Registry: an infrastructure for cooperative multinational, interdisciplinary and translational studies of the genetic epidemiology of breast cancer

Table 7 Distribution of sibships from all sites (1996–2003), by number of affected and unaffected sisters and ascertainment source

Number of affected sisters^a	Number of unaffected sisters^a	Number of sibships
		Population-based case families	Clinic-based families	Total families
1	0	4130	1649	5779
1	1	979	377	1356
1	2	382	105	487
1	≥ 3	157	28	185
2	0	169	118	287
2	1	83	42	125
2	2	46	9	55
2	≥ 3	15	2	17
≥ 3	0	20	14	34
≥ 3	1	8	2	10
≥ 3	2	0	4	4
≥ 3	≥ 3	4	0	4
Total sibships		5993	2350	8343

ISSN: 1465-542X