Table 2. Impact of misclassification between schizophrenia (disorder A) and brief psychotic disorder (disorder B) on estimation of genetic parameters from recurrence risks in first-degree relatives.

				rgT=0			rgT=0.25			rgT=0.5
MTA	MTB	KDA	KD	h2DA	h2DB	rgD	h2DA	h2DB	rgD	h2DA	h2DB	rgD
0	0	1.00	1.00	76	21	0	76	21	25	76	21	50
5	5	1.00	1.00	72	20	25	72	21	44	73	21	63
10	10	1.00	1.00	68	19	45	69	20	59	69	22	73
15	15	1.00	1.00	64	19	62	65	21	72	66	23	82
20	20	1.00	1.00	60	20	75	61	22	81	62	25	88
30	30	1.00	1.00	51	23	91	53	26	93	55	29	96
0	5	1.05	0.95	73	21	3	74	21	27	74	21	51
0	10	1.10	0.90	71	21	6	71	21	29	72	21	52
0	15	1.15	0.85	68	20	9	69	20	31	70	20	54
0	20	1.20	0.80	66	20	12	67	20	33	68	20	55
0	30	1.30	0.70	62	19	17	63	19	37	65	19	57
5	0	0.95	1.05	75	20	22	75	21	41	75	22	61
10	0	0.90	1.10	74	20	38	74	21	54	74	22	70
15	0	0.85	1.15	73	20	52	73	22	64	73	24	77
20	0	0.80	1.20	71	20	63	71	22	72	71	25	82
30	0	0.70	1.30	69	22	77	69	25	83	69	28	89

Parameters for the disorders follow those used in Table 5 of Kendler.⁵ All values are expressed as percentages. The true disease prevalences are assumed to be 1% for both schizophrenia and brief psychotic disorder, K_TA=K_TB=1%. True recurrence risks to first-degree relatives are λ_TA,=8.0, λ_TB=2.0. These parameters equate to true heritabilities on the liability scale of h²_TA=0.76 and h²_TB=0.21. M_TA is the proportion of true schizophrenia cases misclassified as brief psychotic disorder and M_TB is the proportion of true brief psychotic disorder cases misclassified as schizophrenia. The true genetic correlation between the disorders is r_gT=0, 0.25,0.5. The estimated parameters based on diagnosed prevalences and recurrences risks have subscript D.