Growth differentiation factor 15 as a useful biomarker for mitochondrial disorders

Abstract

Objective: The diagnosis of mitochondrial disorders (MDs) is occasionally difficult because patients often present with solitary, or a combination of, symptoms caused by each organ insufficiency, which may be the result of respiratory chain enzyme deficiency. Growth differentiation factor 15 (GDF-15) has been reported to be elevated in serum of patients with MDs. In this study, we investigated whether GDF-15 is a more useful biomarker for MDs than several conventional biomarkers.

Methods: We measured the serum levels of GDF-15 and fibroblast growth factor 21 (FGF-21), as well as other biomarkers, in 48 MD patients and in 146 healthy controls in Japan. GDF-15 and FGF-21 concentrations were measured by enzyme-linked immunosorbant assay and compared with lactate, pyruvate, creatine kinase, and the lactate-to-pyruvate ratio. We calculated sensitivity and specificity and also evaluated the correlation based on two rating scales, including the Newcastle Mitochondrial Disease Rating Scale (NMDAS).

Results: Mean GDF-15 concentration was 6-fold higher in MD patients compared to healthy controls (2,711 ± 2,459 pg/ml vs 462.5 ± 141.0 pg/mL; p < 0.001). Using a receiver operating characteristic curve, the area under the curve was significantly higher for GDF-15 than FGF-21 and other conventional biomarkers. Our date suggest that GDF-15 is the most useful biomarker for MDs of the biomarkers examined, and it is associated with MD severity.

Interpretation: Our results suggest that measurement of GDF-15 is the most useful first-line test to indicate the patients who have the mitochondrial respiratory chain deficiency.

Figure 1

STARD flow diagram and demography of the controls, MD patients, and disease controls. (A) All 48 MD patients who fulfilled the clinical diagnostic criteria (mitochondrial encephalopathy, lactic acidosis, and stroke‐like episodes [MELAS]; mitochondrial encephalopathy, and lactic acidosis [MELA], for which the main symptom was muscle weakness; Leigh syndrome [LS]; overlapping MELAS/LS; and Kearns‐Sayre syndrome [KSS]) and carried a known genetic abnormality were enrolled in this study from 2005 to 2013. (B) Healthy adult and child volunteers without treatment or ambulatory medical care were also recruited in 146 Japanese. MD = mitochondrial disorder; STARD = standards for reporting of diagnostic accuracy.

Figure 2

All biomarker concentrations for MDs and controls, and demography between MDs and non‐MDs patients. (A) GDF‐15, (B) FGF‐21, (C) lactate:pyruvate ratio, (D) lactate, (E) pyruvate, and (F) CK. MD patients exhibited significantly higher levels of all biomarkers compared to controls. CK = creatine kinase; FGF‐21 = fibroblast growth factor 21; GDF‐15 = growth differentiation factor 15; MD = mitochondrial disorder.

Figure 3

Comparison of biomarkers for MDs, and GDF‐15 and FGF‐21 concentrations for MDs and non‐MDs. GDF‐15 and FGF‐21 concentrations in the patients who suffered from MD subtypes, DMD, MS, optic neuritis, limbic encephalitis, brainstem encephalitis, menigoencephalitis, SLE with CNS, NMO, and HUS encephalitis, and HF, and the control group are shown. Each MD subtype displayed significantly higher levels of GDF‐15 and FGF‐21 than the control group. HF displayed significantly higher levels of only GDF‐15 than the control group. (A) GDF‐15 and (B) FGF‐21. CNS = central nervous system; DMD = Duchenne muscular dystrophy; FGF‐21 = fibroblast growth factor 21; GDF‐15 = growth differentiation factor 15; HUS = hemolytic uremic syndrome; KSS = Kearns‐Sayre syndrome; LS = Leigh syndrome; MD = mitochondrial disorder; MS = multiple sclerosis; MELA = mitochondrial encephalopathy, lactic acidosis (mitochondrial myopathy); MELAS = mitochondrial encephalopathy, lactic acidosis, and stroke‐like episodes; NMO = neuromyelitis optica; SLE = systemic lupus erythematosus.

Figure 4

Correlation coefficients between levels of GDF‐15 and FGF‐21 and the JMDRS and NMDAS. GDF‐15 and FGF‐21 levels were positively correlated with the JMDRS and NMDAS: GDF‐15: r = 0.76 (A: p < 0.001) for the JMDRS and r = 0.67 (B: p < 0.001) for the NMDAS; FGF‐21: r = 0.69 (C: p < 0.001) for the JMDRS and r = 0.59 (D: p < 0.001) for the NMDAS. Spearman correlation coefficients were calculated for the statistical analysis. FGF‐21 = fibroblast growth factor 21; GDF‐15 = growth differentiation factor 15; JMDRS = Japanese Mitochondrial Disease Rating Scale; KSS = Kearns‐Sayre syndrome; LS = Leigh syndrome; MELA = mitochondrial encephalopathy, lactic acidosis (mitochondrial myopathy); NMDAS = Newcastle Mitochondrial Disease Adult Scale.

Figure 5

Correlation between GDF‐15 and FGF‐21 for MDs. GDF‐15 and FGF‐21 levels were positively correlated for mitochondrial disorders (MDs): r = 0.64 (p < 0.001). Spearman correlation coefficients were calculated for the statistical analysis. FGF‐21 = fibroblast growth factor 21; GDF‐15 = growth differentiation factor 15.

Figure 6

ROC curves for each biomarker in the MD patients. AUC values were 0.997 (95% confidence interval [CI]: 0.993–1.000) for GDF‐15, 0.919 (95% CI: 0.865–0.973) for the lactate‐to‐pyruvate ratio, 0.889 (95% CI: 0.837–0.962) for FGF‐21, 0.882 (95% CI: 0.814–0.950) for lactate, 0.706 (95% CI: 0.614–0.798) for pyruvate, and 0.609 (95% CI: 0.506–0.711) for creatine kinase (CK). AUC = area under the curve; FGF‐21 = fibroblast growth factor 21; GDF‐15 = growth differentiation factor 15; L/P ratio = lactate‐to‐pyruvate ratio; MD = mitochondrial disorder; ROC = receiver operating characteristic.

Figure 7

GDF‐15 concentrations in the healthy controls reported from literatures. GDF‐15 concentrations were recruited from literatures measured by the same ELISA kit (R&D Systems, Minneapolis, MN), that are a13, b14, c8, d15, e16, f17, g18, h19, and i (our data). Data are shown in mean ± standard deviation (SD). References of a13, d15, and h19 are not described in SD. The number in parenthesis shows sample number. Our GDF‐15 level in the healthy controls was similar to previous literatures.8, 13, 14, 15, 16, 17, 18, 19 GDF‐15 = growth differentiation factor 15.