Hurler Syndrome – Enzyme Analysis

Disease name Hurler Syndrome (MPS I)
Enzyme Name Alpha-iduronidase
Clinical info Mucopolysaccharidosis type I (MPSI) is caused by deficient alpha-iduronidase enzyme activity, which results in an accumulation of the glycoamnioglycan heparan sulfate and dermatan sulfate in body tissues. MPS I is a multisystem progressive disorder demonstrating wide phenotypic variability with three different MPSI subtypes described (Hurler, Hurler-Scheie, and Scheie). Hurler syndrome is considered the more severe end of the phenotypic spectrum with patients generally diagnosed before 18 months of age while Hurler-Scheie and Scheie syndromes are usually used to describe the milder phenotypes. These less severe cases, also known as attenuated MPS I, will often present between 3 and 10 years of age. Clinical features of MPS I include coarse facial features, dysostosis multiplex, short stature, hirsutism, cloudy corneas, and hepatosplenomegaly, and cardiac comlications. Developmental delay and intellectual disability is more severe in those patients with Hurler syndrome and is a distinguishing feature between the subtypes of MPS I.
Indications This test can be used to confirm a suspected Hurler syndrome diagnosis. Prenatal diagnosis and carrier testing via enzyme analysis are not available.
Associated Tests

Measurement of alpha-iduronidase is included in the Lysosomal Enzyme Panel, the Dried Blood Spot Lysosomal Panel, the MPS Panel, MPS urine analysis, and the Storage disease screening panel.
Molecular analysis of the gene for Hurler syndrome (IDUA) is also available for identification of the causative mutation within a family, carrier status and prenatal diagnosis.

Methodology Quantifies level of alpha-fucosidase via the 4-methylumbelliferyl substrate
Specimen Requirements

Enzyme activity can be measured in leukocytes, cultured fibroblasts, or dried blood spots. For leukocytes, please send 5-10 ml of whole blood in a green top (sodium heparin) tube. For dried blood spot collection, a minimum of three circles needs to be filled in. Each circle should contain one drop of blood (about 100 microliters). See the link below for additional sample collection and handling instructions.

Dried Blood Spot Sample Collection and Requirements

In addition, a dried blood spot or blood drawn in an EDTA tube can be used for Hurler syndrome molecular analysis and may be sent for DNA banking. Please indicate on the requisition if DNA should be banked for follow-up molecular testing.


Whole blood samples (for leukocyte analysis) should be shipped at ambient temperature and must arrive at the laboratory within 24 hours of specimen collection.

Cultured fibroblasts should be sent overnight at room temperature.   

For a dried blood spot: When the sample has dried 3-4 hours, fold cover at score line, over sample, and tuck into flap. Samples should be placed in the mail within 24 hours of collection. Overnight shipping is preferred.

Turnaround time 14 days
Cell culture can take 1-4 weeks and may lengthen turnaround time.
CPT Codes 82657
Cost $200
Contact For further information contact one of our This email address is being protected from spambots. You need JavaScript enabled to view it. at 1-800-473-9411.

Cytogenetics Lab

The Cytogenetics Lab provides high quality analysis for the detection of both constitutional chromosomal aberrations as well as abnormalities related to hematological malignancies

Find out more