Carnitine conjugation profiling in a selected cohort of patients with chronic fatigue syndrome

Abstract

Chronic fatigue syndrome (CFS) is classified by the World Health Organisation (WHO) as a non-communicable disease. Fatigue is a symptom commonly experienced by many individuals and is also a symptom associated with a wide variety of diseases, but once this fatigue becomes long lasting, persistent and debilitating, a case of CFS is considered. Research of CFS dates back to the nineteen hundreds, but unfortunately, no definite underlying cause or one single positive treatment has been identified. Diagnosis also poses a difficult task due to different criteria available, but also because of the lack in confidence of diagnosing doctors in making a positive diagnosis, because this disease is still poorly understood. Recent studies and research found promising evidence that mitochondrial dysfunction may be considered as a possible underlying cause of CFS. Because mitochondria are responsible for the release of energy in cells, the connection between mitochondrial dysfunction and the underlying energy deficiency in CFS patients may indicate a good starting point for further investigation. L-carnitine plays an important role in energy metabolism and could possibly be used as potential biomarkers for energy related diseases such as CFS. The first part of the study focused on method development and validation. A pre-existing high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method coupled with electrospray ionisation (ESI) was further developed and validated to simultaneously quantify carnitine and acylcarnitines in human urine samples. The second part of the study included application of the developed and validated method to urine samples of controls and possible CFS patients. All carnitines of interest could be detected and identified with this method, although the longer chain aclylcarnitines posed some difficulty. The aim of this study was to identify altered acylcarnitine profiles associated with possible CFS patients compared to control samples. At the end, principal component analysis (PCA) statistical analysis could not differentiate between the two groups, but two acylcarnitines were identified by the Mann Whitney test to have significant p-values, namely octanoylcarnitine (C8) and decanoylcarnitine (C10).