Chitotriosidase as a biomarker of cerebral adrenoleukodystrophy.
BACKGROUND
Adrenoleukodystrophy (ALD) is an X-linked peroxisomal disorder characterized by the abnormal beta-oxidation of very long chain fatty acids (VLCFA). In 35-40% of children with ALD, an acute inflammatory process occurs in the central nervous system (CNS) leading to demyelination that is rapidly progressive, debilitating and ultimately fatal. Allogeneic hematopoietic stem cell transplantation (HSCT) can halt disease progression in cerebral ALD (C-ALD) if performed early. In contrast, for advanced patients the risk of morbidity and mortality is increased with transplantation. To date there is no means of quantitating neuroinflammation in C-ALD, nor is there an accepted measure to determine prognosis for more advanced patients.


METHODS
As cellular infiltration has been observed in C-ALD, including activation of monocytes and macrophages, we evaluated the activity of chitotriosidase in the plasma and spinal fluid of boys with active C-ALD. Due to genotypic variations in the chitotriosidase gene, these were also evaluated.


RESULTS
We document elevations in chitotriosidase activity in the plasma of patients with C-ALD (n = 38; median activity 1,576 ng/mL/hr) vs. controls (n = 16, median 765 ng/mL/hr, p = 0.0004), and in the CSF of C-ALD patients (n = 38; median activity 4,330 ng/mL/hr) vs. controls (n = 16, median 0 ng/mL/hr, p < 0.0001). In addition, activity levels of plasma and CSF chitotriosidase prior to transplant correlated with progression as determined by the Moser/Raymond functional score 1 year following transplantation (p = 0.002 and < 0.0001, respectively).


CONCLUSIONS
These findings confirm elevation of chitotriosidase activity in patients with active C-ALD, and suggest that these levels predict prognosis of patients with C-ALD undergoing transplantation.
Department of Pediatrics, Program in Blood & Marrow Transplantation, University of Minnesota, Minneapolis, USA. orcha001@umn.edu
Paul J
PJ
Orchard
Troy
T
Lund
Wes
W
Miller
Steven M
SM
Rothman
Gerald
G
Raymond
David
D
Nascene
Lisa
L
Basso
James
J
Cloyd
Jakub
J
Tolar
D000293:Adolescent; D000326:Adrenoleukodystrophy / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology*; D015415:Biomarkers / Q000378:metabolism*; D001921:Brain / Q000473:pathology* / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D005838:Genotype; D006596:Hexosaminidases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male
D015415:Biomarkers; D006596:Hexosaminidases; C086400:chitotriosidase