A new diagnostic indication device of a biomarker GDF15 for mitochondrial diseases: from laboratory to automated inspection.

BACKGROUND Mitochondrial diseases (MDs) are occasionally difficult to diagnose. Growth differentiation factor 15 (GDF15) has been reported as a biomarker useful for not only diagnosing MDs but also evaluating disease severity and therapeutic efficacy. To enable the measurement of serum GDF15 concentrations at medical institutions, we developed a new latex-enhanced turbidimetric immunoassay (LTIA) as an automated diagnostic indication test for MDs. We also examined the equivalency of specificity and sensitivity in measuring serum GDF15 concentrations between a commercially available enzyme-linked immunosorbent assay (ELISA) kit and a novel LTIA device in patients with MDs, disease controls, and healthy controls. METHODS A clinical performance study used a newly developed LTIA device and an existing ELISA kit to measure the concentrations of GDF15 in 35 MD patients, 111 disease controls, and 86 healthy controls. RESULTS The median [first quartile-third quartile] of serum GDF15 concentrations measured with the LTIA device was significantly higher (p <0.001) in MD patients (1,389.0 U/ml [869.5-1,776.0 U/ml]) than in healthy controls (380.5 U/ml [330.2-471.8 U/ml]); the interquartile ranges did not overlap between MD patients and healthy controls. The areas under the curve in disease and healthy controls were 0.812 [95% confidence interval (CI): 0.734-0.886] and 0.951 [95% CI: 0.910-0.992], respectively. The automated, high-throughput technology-based LTIA device has definite advantages over the ELISA kit in shorter processing time and lower estimated cost per sample measurement. CONCLUSIONS The LTIA device of GDF15 may be a sufficiently reliable, frontline, diagnostic indicator of individuals with suspected MDs in the general population. This article is protected by copyright. All rights reserved.