Table 1

Review of reported cases with BRCA1/BRCA2 double heterozygosity

No	DH (index) cases*	Mutations‡		FH: maternal/ paternal§	Inheritance confirmed?	Reference
*Diagnosis, age at diagnosis (years); (_), age at last follow up.
†Assumed to have both mutations.
‡Documented founder mutations in bold type; 185delAG and 187delAG are identical, 5382insC and 5385insC are identical.
§Family history of breast and/or ovarian cancer.
AZG, Groningen University Hospital; BC, breast cancer; Bilat, bilateral; DH, double heterozygosity; FH, family history; Neg, negative; OC, ovarian cancer; Pos, positive; UMCN, University Medical Centre Nijmegen; ??, no information available.
1	OC 40 and BC 45 (51)	BRCA1	2804delAA	Pos/Neg	Both mutations familial, maternal/paternal origin undetermined	This report (AZG)
		BRCA2	3715delG	Pos/Neg

2	BC 28 (49)	BRCA1	2804delAA	Neg/Neg	No information available	This report (UMCN)
		BRCA2	4677delA	Neg/Neg

3	Healthy 40	BRCA1	185delAG	Pos/??	Two maternal cousins 185delAG, 6174delT probably paternal	This report (UK)
		BRCA2	6174delT	Pos/??	Two maternal cousins 185delAG, 6174delT probably paternal

4	BC 51 (68)	BRCA1	5382insC	Pos/??	Maternal niece 5382insC, origin 6174delT unknown	This report (UK)
		BRCA2	6174delT	Pos/??	Maternal niece 5382insC, origin 6174delT unknown

5	BC <39	BRCA1	187delAG	Neg/Neg	No information available	This report/Frank et al²³
		BRCA2	6174delT	Neg/Neg

6	BC 40	BRCA1	5385insC	??/??	No information available	This report/Frank et al²³
		BRCA2	6174delT	??/??

7	BC 41	BRCA1	187delAG	Pos	No information available	This report/Frank et al²³
		BRCA2	6174delT	Neg

8	Bilat BC 34	BRCA1	187delAG	Pos	No information available	This report/Frank et al²³
		BRCA2	6174delT	Pos

9	Bilat BC 33 (49)	BRCA1	5385delAG	??	No information available	This report/Frank et al²³
		BRCA2	6174delT	??

10	Bilat BC 55 (56)	BRCA1	187delAG	Pos	No information available	This report/Frank et al²³
		BRCA2	6174delT	Neg

11	Healthy 61	BRCA1	5385insC	Pos	No information available	This report/Frank et al²³
		BRCA2	6174delT	Neg

12	Healthy 66	BRCA1	187delAG	Pos	No information available	This report/Frank et al²³
		BRCA2	6174delT	Neg

13	BC 48 and OC 50	BRCA1	185delAG	Pos	No information available	Ramus et al¹⁰
		BRCA2	6174delT	??

14	Index BC 38	BRCA1	185delAG	Pos	Father had neither mutation, mother assumed carrier of both mutations	Friedman et al¹¹ (pat No 1)
15	Mother OC 50†	BRCA2	6174delT	Pos

16	OC 57 (62)	BRCA1	185delAG	Pos	No information available	Friedman et al¹¹ (pat No 2)
		BRCA2	6174delT	??

17	Healthy 50	BRCA1	185delAG	Pos	No information available	Friedman et al¹¹ (pat No 3)
		BRCA2	6174delT	??

18	BC 45 (46)	BRCA1	5382insC	Pos	5382insC assumed to be maternal	Friedman et al¹¹ (pat No 4)
		BRCA2	6174delT	??

19	BC 35	BRCA1	2508G→T	Pos	Mother neither mutation, no other family members available	Liede et al¹²
		BRCA2	3295insA	Pos	Mother neither mutation, no other family members available

20	BC 30 and OC 41	BRCA1	3888delGA	Pos	Mother and sister 6174delT; father 3888delGA	Randall et al⁷
		BRCA2	6174delT	Neg.	Mother and sister 6174delT; father 3888delGA

21	BC <40	BRCA1	3888delGA	??	Father 6174delT; neither parent 3888delGA; 3888delGA assumed paternal de novo	Tesoriero et al¹³
		BRCA2	6174delT	??

22	Index healthy 36	BRCA1	185delAG	Pos	Brother and father neither mutation; sister only 185delAG; mother assumed carrier of both mutations	Moslehi et al¹⁴
23	Mother OC 36†	BRCA2	6174delT	Pos


24	BC 33 and 44 and 47	BRCA1	5382insC	Neg	No information available	Bell et al¹⁵
		BRCA2	6174delT	Pos

25	Index BC 28	BRCA1	5242C→T	Pos	Mother both mutations	Caldes et al¹⁶
26	Mother healthy 70	BRCA2	6503delTT	??
27	Sister healthy 40
28	Cousin healthy 47
29	Cousin healthy 41
30	Aunt BC 70
31	Aunt BC 66

32	Index BC 33	BRCA1	E1661X	Neg	Mother both mutations	Choi et al²⁰ (pat 60071)
33	Mother stomach cancer 62	BRCA2	6174del4	Neg		Choi et al²⁰ (pat 60071)

34	Index BC 26	BRCA1	1635del5	Neg	No information available	Choi et al²⁰ (pat 60351)
		BRCA2	3026delCA	Neg		Choi et al²⁰ (pat 60351)