Elevated sulfatide excretion in heterozygotes of metachromatic leukodystrophy: dependence on reduction of arylsulfatase A activity.

Sulfatide excretion in urine and arylsulfatase A (ASA) activity in leukocytes were determined in 10 homozygotes of metachromatic leukodystrophy (MLD), 7 obligate and 5 facultative MLD heterozygotes, 6 low ASA subjects (not related to MLD homozygotes), and in 9 controls. As compared to controls (sulfatides: 0-2 nmol/mg lipid; ASA: 101-287 nmol p-nitrocatechol/mg protein/hr), MLD homozygotes displayed highly increased sulfatide excretions (27-280 nmol) and low residual ASA activities (0-13 nmol). Of 12 MLD heterozygotes (ASA: 18-87 nmol) 10 showed increased sulfatides (3-24 nmol). All heterozygotes with ASA activity < 60 nmol (n = 8) had elevated sulfatide excretions (4-24 nmol). Thus, reduction of ASA activity below 40% of the mean value of controls seems to be the critical threshold for elevated sulfatide excretion in MLD heterozygotes. The low ASA subjects (ASA in the heterozygote range) excreted sulfatides in the control range, even those with ASA activities < 60 nmoles (n = 3; including a definite homozygote for ASA-pseudodeficiency; ASA:25 nmol). Statistical evaluation of sulfatide excretion and ASA activity in all subjects (n = 37) revealed a significant inverse relation (Spearman rank correlation; R = 0.8278, P < 0.001). The finding of elevated sulfatide excretion in certain MLD heterozygotes might point to increase of sulfatides also in the nervous system.

Phytanic acid and very long chain fatty acids in genetic peroxisomal disorders.

1. Phytanic acid, phytanyl-triacylglycerols, and very long chain fatty acids were analysed by gas chromatography or thin-layer chromatography in blood and tissues of patients with different genetic peroxisomal disorders (Refsum's disease, X-linked adrenoleukodystrophy, neonatal adrenoleukodystrophy, Zellweger syndrome). 2. We evaluated these analyses in the detection of patients with Refsum's disease, X-linked adrenoleukodystrophy, neonatal adrenoleukodystrophy, and Zellweger syndrome, and of carriers of X-linked adrenoleukodystrophy. In particular, the analysis of phytanyl-triacylglycerols by thin-layer chromatography proved to be a rapid and reliable method for the detection of patients and the monitoring of their dietary treatment in Refsum's disease. In X-linked adrenoleukodystrophy, carrier detection may depend on very long chain fatty acid analysis in more than one material (e.g. plasma and fibroblasts). 3. Analysis of phytanic acid showed that in patients with multiple impairments of peroxisomal functions (Zellweger syndrome, neonatal adrenoleukodystrophy) phytanic acid levels may be increased not only in serum, but also in the tissue (e.g. brain, adrenals, kidney). 4. Analysis of very long chain fatty acids in cholesterol esters from the brain, adrenals, kidney, and liver of patients with peroxisomal disorders revealed four different types of very long chain fatty acid patterns according to the behaviour of C 26:0 and of other saturated and monounsaturated very long chain fatty acids.(ABSTRACT TRUNCATED AT 250 WORDS)