FGF23 and Behcet disease: However, C-FGF23 was a significant predictor of I-FGF23 concentration in BD children (coefficient % (s.e.m.): 30 (12) %; R2=24%; P=0.03) but not in LC children (coefficient % (s.e.m.): LC+=−2.5 (6.5)%; R2=0.8%; P=0.7; LC−=6.4 (10.3)%; R2=1.7%; P=0.5) (Fig. 1B).