Bio-Plex immunoassay measuring the quantity of lysosomal N-acetylgalactosamine-6-sulfatase protein in dried blood spots for the screening of mucopolysaccharidosis IVA in newborn: a pilot study.

Abstract

OBJECTIVE:

Mucopolysaccharidosis (MPS) IVA (Morquio syndrome A) is an autosomal-recessive lysosomal storage disorder caused by the deficiency of N-acetylgalactosamine-6-sulfatase (GALNS) resulting in excessive lysosomal storage of keratan sulfate. Treatments for MPS IVA have recently become available with optimal outcomes associated with early diagnosis and treatment which can be achieved by newborn screening.

DESIGN:

Newborn screening programme for MPS IVA pilot study.

SETTING:

MacKay Memorial Hospital (MMH), Taipei and another three branch hospitals in Taiwan.

PARTICIPANTS:

A total of 7415 newborns were born in four branch hospitals of MMH and had joined the MPS IVA newborn screening programme. Written informed consents were obtained from parents prior to the screening process (12MMHIS188 approved by MacKay Memorial Hospital Institutional Review Board).

OUTCOME MEASURES:

An alternative newborn screening method for MPS IVA has been performed. Screening involved measuring the quantity of GALNS in dried blood spot (DBS) from newborn infants using the Bio-Plex immunoassay. The amount of fluorescence sorting detected by yttrium aluminium garnet laser was proportional to the quantity of GALNS protein.

RESULTS:

Of the 7415 neonates analysed, eight infants whose GALNS levels were below the cut-off value of 8.30 µg/L had been recalled for a second DBS collection. The reference values were 8.30-27.43 µg/L. In patients with confirmed MPS IVA (n=11), the GALNS quantities were far below 5% of the normal population.

CONCLUSION:

The Bio-Plex immunoassay is a validated method used for measuring GALNS protein in DBS and has the potential to be adopted for MPS IVA newborn screening study design.

• Authors: Chih-Kuang Chuang, Hsiang-Yu Lin, Tuan-Jen Wang, Sung-Fa Huang, Shuan-Pei Lin
• Journal: BMJ open (BMJ Open) Vol. 7 Issue 7 Pg. e014410 (Jul 13 2017) ISSN: 2044-6055 [Electronic] England
• PMID: 28710204 (Publication Type: Journal Article, Multicenter Study, Validation Study)
• Copyright: © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Chemical References

• Chondroitinsulfatases
• GALNS protein, human

Topics

• Chondroitinsulfatases (blood)
• Dried Blood Spot Testing
• Female
• Humans
• Immunoassay (methods)
• Infant, Newborn
• Logistic Models
• Male
• Mucopolysaccharidosis IV (diagnosis, epidemiology)
• Neonatal Screening
• Pilot Projects
• Taiwan (epidemiology)