Factors associated with IgG levels in adults with IgG subclass deficiency

BMC Immunology

Table 1 Characteristics of 39 adults with IgGSD and subnormal IgG1 only^a

Characteristics	IgG < 7.00 g/L, % (n = 15)	IgG ≥ 7.00 g/L, % (n = 24)	Value of p
Women, % (n)	100.0 (15)	83.3 (20)	0.1458
Mean age at diagnosis, y ± 1 SD	53 ± 15	45 ± 14	0.1196
Autoimmune condition(s), % (n)^b	26.7 (4)	62.5 (15)	0.0484
Atopy, % (n)^c	33.3 (5)	20.8 (5)	0.4633
Autoimmune condition(s) and atopy, % (n)	3.3 (2)	4.2 (1)	0.5470
Mean IgG, g/L ± 1 SD	6.10 ± 0.57	8.19 ± 0.85	< 0.0001
Median IgG1, g/L (range)	3.21 (2.82, 4.12)	3.89 (3.27, 4.18)	< 0.0001
Median IgG2, g/L (range)	2.28 (1.25, 3.92)	3.04 (1.66, 5.96)	0.0147
Median IgG3, g/L (range)	0.55 (0.41, 1.14)	0.66 (0.43, 1.38)	0.1057
Median IgG4, g/L (range)	0.12 (0.01, 0.86)	0.16 (0.01, 0.54)	0.9424
Mean IgA, g/L ± 1 SD	1.74 ± 0.82	1.91 ± 0.73	0.5374
Median IgM, g/L (range)	1.18 (0.50, 4.08)	0.96 (0.40, 2.79)	0.3054

^aIgGSD, IgG subclass deficiency; SD, standard deviation. Subnormal IgG1 is defined as a value < 2 SD below the mean. No patient had subnormal serum levels of IgG2, IgG3, IgG4, IgA, or IgM. One of 35 women (2.9%) had elevated IgG3. Six of 35 women (17.1%) had elevated IgM. Neither elevated IgG3 nor elevated IgM was observed in the four men represented herein
^bAutoimmune condition(s) were diagnosed in 19 patients: ankylosing spondylitis (2); autoimmune thyroiditis (9); Behçet disease (1); Graves disease (2); inflammatory arthritis (1); myasthenia gravis (1); pernicious anemia (1); psoriasis (2); rheumatoid arthritis (1); Sjögren syndrome (3); systemic lupus erythematosus (2); and undifferentiated connective tissue disorder (2). Seven of the 19 patients (36.8%) had two or more autoimmune conditions
^cAtopy was diagnosed in 10 patients (7 allergic asthma, 4 allergic rhinitis, 1 allergic dermatitis). Two of the 10 patients (20.0%) had two atopy conditions

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