Very Long Chain Fatty Acids (VLCFAs), Phytanic acid and Pristanic acid are metabolized by Peroxisomes. Defects in these pathways usually result in the accumulation in tissues and body fluids of one or more metabolites derived from the blocked metabolic steps. This assay is used for differential diagnosis of peroxisomal disorders like Zellweger spectrum disorders of peroxisomal biogenesis, X-linked Adrenoleukodystrophy (X-ALD) and its adult form X-linked Adrenomyeloneuropathy (X-AMN), Refsum disease (Phytanoyl-CoA hydroxylase Deficiency) & 2-methylacyl-CoA racemase deficiency.\n