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Recently IMP has been informed about a study which has been carried out at the University of Helsinki, Finland, into diagnostic methods for mitochondrial disease. Up to now the only reliable diagnostic method exists of a muscle biopsy, which is a rather interfering and radical method for the patient. In search of other diagnostic measures with biomarkers, the finnish researchers carried out a study into the value of FGF-21 (a protein) for diagnostic use. One of the findings is that FGF-21 might be feasible as a first-line diagnostic test for mitochondrial disorders to reduce the need for muscle biopsy.

 

PLEASE FIND HEREWITH THE ABSTRACT OF THE STUDY AS IT WAS PUBLISHED ON PUBMED.ORG AND IN THE LANCET NEUROLOGY OF SEPTEMBER 2011

http://www.ncbi.nlm.nih.gov/pubmed/21820356

FGF-21 AS A BIOMARKER FOR MUSCLE-MANIFESTING MITOCHONDRIAL RESPIRATORY CHAIN DEFICIENCIES: A DIAGNOSTIC STUDY.

Suomalainen A, Elo JM, Pietiläinen KH, Hakonen AH, Sevastianova K, Korpela M, Isohanni P, Marjavaara SK, Tyni T, Kiuru-Enari S, Pihko H, Darin N, Õunap K, Kluijtmans LA, Paetau A, Buzkova J, Bindoff LA, Annunen-Rasila J, Uusimaa J, Rissanen A, Yki-Järvinen H, Hirano M, Tulinius M, Smeitink J, Tyynismaa H.

Source: Research Programmes Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland. This email address is being protected from spambots. You need JavaScript enabled to view it.

BACKGROUND

Muscle biopsy is the gold standard for diagnosis of mitochondrial disorders because of the lack of sensitive biomarkers in serum. Fibroblast growth factor 21 (FGF-21) is a growth factor with regulatory roles in lipid metabolism and the starvation response, and concentrations are raised in skeletal muscle and serum in mice with mitochondrial respiratory chain deficiencies. We investigated in a retrospective diagnostic study whether FGF-21 could be a biomarker for human mitochondrial disorders.

METHODS

We assessed samples from adults and children with mitochondrial disorders or non-mitochondrial neurological disorders (disease controls) from seven study centres in Europe and the USA, and recruited healthy volunteers (healthy controls), matched for age where possible, from the same centres. We used ELISA to measure FGF-21 concentrations in serum or plasma samples (abnormal values were defined as >200 pg/mL). We compared these concentrations with values for lactate, pyruvate, lactate-to-pyruvate ratio, and creatine kinase in serum or plasma and calculated sensitivity, specificity, and positive and negative predictive values for all biomarkers.

FINDINGS

We analysed serum or plasma from 67 patients (41 adults and 26 children) with mitochondrial disorders, 34 disease controls (22 adults and 12 children), and 74 healthy controls. Mean FGF-21 concentrations in serum were 820 (SD 1151) pg/mL in adult and 1983 (1550) pg/mL in child patients with respiratory chain deficiencies and 76 (58) pg/mL in healthy controls. FGF-21 concentrations were high in patients with mitochondrial disorders affecting skeletal muscle but not in disease controls, including those with dystrophies. In patients with abnormal FGF-21 concentrations in serum, the odds ratio of having a muscle-manifesting mitochondrial disease was 132·0 (95% CI 38·7-450·3). For the identification of muscle-manifesting mitochondrial disease, the sensitivity was 92·3% (95% CI 81·5-97·9%) and specificity was 91·7% (84·8-96·1%). The positive and negative predictive values for FGF-21 were 84·2% (95% CI 72·1-92·5%) and 96·1 (90·4-98·9%). The accuracy of FGF-21 to correctly identify muscle-manifesting respiratory chain disorders was better than that for all conventional biomarkers. The area under the receiver-operating-characteristic curve for FGF-21 was 0·95; by comparison, the values for other biomarkers were 0·83 lactate (p=0·037, 0·83 for pyruvate (p=0·015), 0·72 for the lactate-to-pyruvate ratio (p=0·0002), and 0·77 for creatine kinase (p=0·013).

INTERPRETATION

Measurement of FGF-21 concentrations in serum identified primary muscle-manifesting respiratory chain deficiencies in adults and children and might be feasible as a first-line diagnostic test for these disorders to reduce the need for muscle biopsy.

FUNDING

Sigrid Jusélius Foundation, Jane and Aatos Erkko Foundation, Molecular Medicine Institute of Finland, University of Helsinki, Helsinki University Central Hospital, Academy of Finland, Novo Nordisk, Arvo and Lea Ylppö Foundation.

Copyright © 2011 Elsevier Ltd. All rights reserved.

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