Quantification of sulfatides in dried blood and urine spots from metachromatic leukodystrophy patients by liquid chromatography/electrospray tandem mass spectrometry

Abstract

Background: Treatments are being developed for metachromatic leukodystrophy (MLD), suggesting the need for eventual newborn screening. Previous studies have shown that sulfatide molecular species are increased in the urine of MLD patients compared to samples from non-MLD individuals, but there is no data using dried blood spots (DBS), the most common sample available for newborn screening laboratories.

Methods: We used ultra-high performance liquid chromatography/tandem mass spectrometry (UHPLC/MS/MS) to quantify sulfatides in DBS and dried urine spots from 14 MLD patients and 50 non-MLD individuals.

Results: Several sulfatide molecular species were increased in dried urine samples from all MLD samples compared to non-MLD samples. Sulfatides, especially low molecular species, were increased in DBS from MLD patients, but the sulfatide levels were relatively low. There was good separation in sulfatide levels between MLD and non-MLD samples when dried urine spots were used, but not with DBS, because DBS from non-MLD individuals have measurable levels of sulfatides.

Conclusion: Sulfatide accumulation studies in urine, but not in DBS, emerges as the method of choice if newborn screening is to be proposed for MLD.

Keywords: Dried blood spots; Lysosomal storage diseases; Metachromatic leukodystrophy; Newborn screening; Sulfatides; Tandem mass spectrometry; Urine.