Table 2. Frequencies of mtDNA haplogroups in Han Chinese patients with SLE and healthy controls.

Group or subgroup	mtDNA haplogroup, n (%)		P	OR	95%CI
	M	N
Patients with SLE	429 (49.4)	439 (50.6)	0.213*
<50 years old at onset age	406 (50.1)	405 (49.9)	0.861#
≧50 years old at onset age	23 (40.4)	34 (59.6)	0.042Δ	2.070	1.021 to 4.196
Healthy controls	456 (52.4)	414 (47.6)
<50 years old	396 (49.6)	402 (50.4)
≧50 years old	42 (58.3)	30 (41.7)

^*between all patients and controls.

^#between patients younger than 50 years at onset age and controls younger than 50 years.

^Δbetween patients 50 years or older at onset age and controls 50 years or older.