Detection of Characteristic Phosphatidylcholine Containing Very Long Chain Fatty Acids in Cerebrospinal Fluid from Patients with X-Linked Adrenoleukodystrophy

X-linked Adrenoleukodystrophy (X-ALD) is a rare genetic neurological disorder caused by a mutation of the ABCD1 gene that encodes a peroxisomal ABC protein ABCD1. ABCD1 has a role in transporting very long chain fatty acid (VLCFA)-CoA into the peroxisome for β-oxidation. ABCD1 dysfunction leads to reduced VLCFA β-oxidation and in turn increased VLCFA levels in the plasma and the cells of all tissues; these increased plasma levels have been used to diagnose X-ALD. It has been reported that plasma VLCFA is not correlated with the severity and disease phenotype of X-ALD. Therefore, we cannot predict the disease progression by the plasma VLCFA level. Cerebrospinal fluid (CSF) is constantly produced by brain, and thus levels of lipids containing VLCFA in CSF might be informative in terms of assessing X-ALD pathology. LC-MS/MS-based analysis showed that phosphatidylcholine (PC) containing VLCFA signals, such as PC 40:0(24:0/16:0), PC 42:0(26:0/16:0), PC 44:4(24:0/20:4) and PC 46:4(26:0/20:4) were characteristically detected only in the CSF from patients with X- ALD. In the present study, we analyzed limited number of patient’s CSF samples (2 patients with X-ALD) due to the limitations of the availability for CSF samples from this rare disease. However, our finding would offer helpful information for studying the disease progression biomarkers in X-ALD. To our knowledge, this is the first report of analyzing lipids containing VLCFA in CSF from patients with X-ALD.