Factors associated with IgG levels in adults with IgG subclass deficiency

BMC Immunology

Table 2 Characteristics of 53 adults with IgGSD and combined subnormal IgG1/IgG3^a

Characteristics	IgG < 7.00 g/L, % (n = 32)	IgG ≥ 7.00 g/L, % (n = 21)	Value of p
Women, % (n)	93.8 (30)	50.9 (17)	0.1995
Mean age at diagnosis, y ± 1 SD	52 ± 14	50 ± 10	0.5653
Autoimmune condition(s), % (n)^b	28.1 (9)	38.1 (8)	0.5511
Autoimmune condition(s) and atopy, % (n)	0	0	1.0000
Atopy, % (n)^c	31.3 (10)	38.1 (8)	0.4633
Mean IgG, g/L ± 1 SD	6.07 ± 0.68	8.73 ± 1.20	< 0.0001
Mean IgG1, g/L ± 1 SD	3.11 ± 0.55	3.70 ± 0.41	< 0.0001
Mean IgG2, g/L ± 1 SD	2.41 ± 0.67	4.02 ± 1.15	< 0.0001
Mean IgG3, g/L ± 1 SD	0.29 ± 0.09	0.31 ± 0.07	0.4188
Median IgG4, g/L (range)	0.21 (0.02, 0.49)	0.21 (0.01, 0.88)	0.5010
Median IgA, g/L (range)	1.77 (0.86, 13.09)	1.94 (1.26, 4.47)	0.2713
Median IgM, g/L (range)	0.98 (0.41, 4.07)	1.19 (0.45, 4.15)	0.6364

^aIgGSD, IgG subclass deficiency; SD, standard deviation. Subnormal IgG1/IgG3 is defined as values < 2 SD below the respective means. No patient had subnormal serum levels of IgG2, IgG4, IgA, or IgM. Three of 47 women (6.4%) had elevated IgA. Six of 47 women (12.8%) had elevated IgM. Neither elevated IgG3 or elevated IgM was observed in the six men represented herein
^bAutoimmune condition(s) were diagnosed in 17 patients: ankylosing spondylitis (1); autoimmune thyroiditis (9); Graves disease (1); multiple sclerosis (1); pernicious anemia (1); polymyalgia rheumatica (1); rheumatoid arthritis (2); Sjögren syndrome (1); and undifferentiated connective tissue disorder (1). One of the 18 patients (5.6%) had two autoimmune conditions
^cAtopy was diagnosed in 18 patients (15 allergic asthma, 3 allergic rhinitis, 2 allergic dermatitis). Two of the 18 patients (11.1%) had two atopy conditions

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