Table 1.

Maternal–offspring HLA–DRB1 compatibility in SLE families compared with paternal–offspring compatibility (father controls) and independent healthy maternal–offspring pairs (healthy controls)^*

	SLE, no. (%)	Father controls			Healthy controls
HLA–DRB1 compatibility		No. (%)	OR (95% CI)	P†	No. (%)	OR (95% CI)	P†
Overall‡
Unidirectional child-to-parent	96 (13.6)	93 (13.2)	1.01 (0.73–1.41)	0.94	17 (9.0)	1.32 (0.91–2.98)	0.10
Unidirectional parent-to-child	74 (10.5)	72 (10.2)	1.01 (0.70–1.46)	0.99	22 (11.7)	0.85 (0.56–1.68)	0.89
Bidirectional	87 (12.3)	99 (14.0)	0.87 (0.62–1.20)	0.38	21 (11.2)	0.65 (0.69–2.08)	0.61
Not increased	450 (63.6)	443 (62.7)	Reference		128 (68.1)	Reference
Male and nulligravid female SLE offspring§
Unidirectional child-to-parent	27 (13.9)	25 (12.9)	0.96 (0.50–1.82)	0.88	17 (9.0)	1.56 (0.78–3.21)	0.19
Unidirectional parent-to-child	15 (7.7)	19 (9.8)	0.70 (0.31–1.53)	0.36	22 (11.7)	0.67 (0.31–1.43)	0.29
Bidirectional	22 (11.3)	35 (18.0)	0.56 (0.29–1.04)	0.06	21 (11.2)	1.03 (0.51–2.08)	0.99
Not increased	130 (67.0)	115 (59.3)	Reference		128 (68.1)	Reference

^*Histocompatibility was estimated using 2-digit DRB1 typing resolution. SLE = systemic lupus erythematosus; OR = odds ratio; 95% CI = 95% confidence interval.

^†By Fisher’s exact test.

^‡Comparing 707 maternally affected offspring pairs with 707 paternally affected offspring pairs and 188 independent healthy controls.

^§Comparing 194 maternally affected offspring pairs in which the affected offspring was either a male or a nulligravid female with 194 paternally affected offspring pairs and 188 independent healthy controls.