N-acetylgalactosamine-6-sulfatase protein detection in MPS IVA patient and unaffected control samples.
BACKGROUND
Mucopolysaccharidosis type IVA (MPS IVA; Morquio syndrome) is a lysosomal storage disorder caused by a deficiency in the activity of the lysosomal hydrolase N-acetylgalactosamine-6-sulfatase (GALNS). MPS IVA patients can present with severe myelopathy, hearing loss, heart valve involvement, short trunk/dwarfism and corneal clouding. Early diagnosis of MPS IVA will allow potential treatments to be implemented before the onset of irreversible pathology.


METHODS
We have developed a sensitive immune-quantification assay for the accurate detection of GALNS protein in skin fibroblasts, blood and plasma from unaffected control and MPS IVA patients.


RESULTS
MPS IVA patient fibroblast extracts (n=11) had non-detectable (ND)-10 ng/mg of 6-sulfatase protein compared to 3-82 ng/mg for normal controls (n=19). Dried blood-spots from MPS IVA patients (n=4) contained ND-1.3 ng/L of 6-sulfatase protein compared to 18-145 ng/L for normal controls (n=49). Plasma from MPS IVA patients (n=7) contained ND 6-sulfatase protein compared to 1-9 ng/L for normal controls (n=49).


CONCLUSIONS
The immune assay described here had the capacity to accurately measure the amount of GALNS protein in various biological samples, providing the basis of an assay that could be further developed to enable newborn and high-risk population screening for MPS IVA patients.
Parkinson-Lawrence
Emma J
EJ
Lysosomal Diseases Research Unit, Department of Genetic Medicine, Children Youth and Women's Health Service, and Department of Pediatrics, University of Adelaide, Adelaide, South Australia 5005, Australia.
Muller
Viv J
VJ
Hopwood
John J
JJ
Brooks
Doug A
DA
D002478:Cells, Cultured; D002811:Chondroitinsulfatases / Q000032:analysis* / Q000276:immunology / Q000378:metabolism*; D006262:Health; D006801:Humans; D007118:Immunoassay; D009085:Mucopolysaccharidosis IV / Q000145:classification* / Q000201:enzymology*; D012867:Skin / Q000378:metabolism
D002811:Chondroitinsulfatases; C102295:GALNS protein, human