Table 2.

Recurrence risks for schizophrenia and bipolar disorders and co-morbidity in parent-offspring and siblings.

Proband	Relation to proband	Risk for schizophrenia when proband has schizophrenia		Risk for bipolar disorder when proband has bipolar disorder		Risk for schizophrenia when proband has bipolar disorder		Risk for bipolar disorder when proband has schizophrenia
		Relative Risk	95% CI	Relative Risk	95% CI	Relative Risk	95% CI	Relative Risk	95% CI
Parent	Offspring	9.9	8.5–11.6	6.4	5.9–7.1	2.4	2.1–2.6	5.2	4.4–6.2
Sibling	Sibling	9.0	8.1–9.9	7.9	7.1–8.8	3.9	3.4–4.4	3.7	3.2–4.2
Sibling	Maternal half-sibling	3.6	2.3–5.5	4.5	2.7–7.4	1.4	0.7–2.6	1.2	0.6–2.4
Sibling	Paternal half-sibling	2.7	1.9–3.8	2.4	1.4–4.1	1.6	1.0–2.7	2.2	1.3–3.8
Adoptive relationships
Biological parent	Adopted away offspring	13.7	6.1–30.8	4.3	2.0–9.5	4.5	1.8–10.9	6.0	2.3–15.2
Sibling	Adopted away biological sibling	7.6	0.7–87.8	-		3.9	0.2–63.3	5.0	0.3–79.9
Adoptive parent	Adoptee	-		1.3	0.5–3.6	1.5	0.7–3.5	-
Sibling	Non-biological sibling	1.3	0.1–15.1	-		-		2.0	0.1–37.8