Lipid signature in X-ALD: a comparison between phenotypes

Abstract

X-linked adrenoleukodystrophy (X-ALD) has highly variable phenotypes with no known genotype/phenotype correlation or method for predicting the course of the disease. Screening for X-ALD allows for early, potentially lifesaving treatment of adrenal insufficiency and cerebral demyelination, possibly useful to detect pre-clinical differences in patients and extend treatments to pre-symptomatic subjects. In this study, we analyzed the lipid signature in fibroblasts of patients with Adrenomyeloneuropathy (AMN), the late onset and slowly progressive form of X-ALD, and in patients with Cerebral Adrenoleukodystrophy (CALD), the cerebral inflammatory demyelinating form of early childhood, in order to identify specific lipid molecules as potential early predictors for CALD. We analyzed lipidomic profiles in fibroblasts obtained from n = 4 clinically affected (and genetically proven) X-ALD patients (two CALD and two AMN) and n = 4 age-matched controls, using a Dionex UltiMate 3000 UHPLC system, coupled to a Q-Exactive mass spectrometer. Our results highlight alterations in lipid metabolism both in AMN and in CALD fibroblasts relative to controls, further confirming the role of LPC 26:0 as a potential biomarker of X-ALD. However, the extent and pattern of lipid remodeling differ substantially between the two phenotypes, with a contribution of neutral lipids in CALD patients, along with a selective involvement of gangliosides. Although both AMN and CALD fibroblasts share some disease-associated lipid alterations, CALD samples exhibited a broader and more pronounced perturbation in multiple lipid classes, particularly in LPCs and steryl esters. The identification of phenotype-associated lipid signatures may represent a step forward toward precision medicine in X-ALD, in order to improve patient phenotypic evaluation.