Table 2

Frequency and diagnostic sensitivity and specificity of ACPA isotypes and RF isotypes in first-degree relatives and RA patients from multicase families

	Frequency	Sensitivity	Specificity
	First-degree relatives, n (%)	Patients with RA, n (%)	%
IgG anti-CCP	34 (21.7)^***	140 (85.9)^***	98
IgA anti-CCP	42 (26.8)^***	118 (72.4)^***	99
IgM anti-CCP	35 (22.3)^***	74 (45.4)^***	94
IgM-RF	22 (14.0)^*	121 (74.2)^***	95
IgA-RF	35 (22.3)^***	123 (75.5)^***	94

↵* p< 0.05,
↵*** p<0.001,
patients with RA and first-degree relatives versus healthy controls.
ACPA, anti-citrullinated protein/peptide antibody; CCP, cyclic citrullinated peptide; RA, rheumatoid arthritis; RF, rheumatoid factor.