Extremely low level of serum pigment epithelium-derived factor is a special biomarker of Chinese osteogenesis imperfecta patients with SERPINF1 mutations.

Backgrounds: SERPINF1 mutations caused deficiency of pigment epithelium-derived factor (PEDF) and would lead to osteogenesis imperfecta (OI) type VI. However, serum PEDF levels were unclear in Chinese OI patients who had clear molecular diagnosis.

Objective: To assess PEDF levels in different genotypes of OI, to evaluate the influencing factors of PEDF in Chinese OI patients with clear molecular diagnosis.

Methods: Known candidate genes of OI were examined by a targeted next generation sequence. Serum PEDF levels were measured by ELISA in 6 OI patients with SERPINF1 mutations, 6 carriers of one copy of the SERPINF1 mutation, 88 OI patients with COL1A1, CLO1A2, IFITM5 and other pathogenic mutations of OI and 24 healthy controls. We compared the differences in serum PEDF levels among different OI patients and normal controls.

Results: Serum PEDF levels were extremely low in OI patients with SERPINF1 mutations (0.66±1.60μg/ml) than in OI patients with other pathogenic mutations (4.88±1.43-7.07±2.43μg/ml), carriers of one copy of SERPINF1 mutation (4.94±2.35μg/ml), and normal controls (7.29±2.31μg/m) (P<0.001). No significant differences in serum PEDF concentrations were found among patients with OI type I, III or IV, and between patients with or without bisphosphonate treatment. Serum PEDF level was positively correlated with Z-score of weight (r=0.310, P=0.004), BMI (r=0.253, P=0.020) and alanine aminotransferase (r=0.291, P=0.007).

Conclusions: Extremely low level of PEDF was demonstrated as a specific, convenient, and inexpensive diagnostic biomarker for OI patients with SERPINF1 mutations, but it could not provide information regarding the clinical severity of OI and the efficacy of bisphosphonates treatment.