Hurler Syndrome (MPS I): IDUA Sequencing

Test Information

IDUA sequencing is a molecular test used to identify variants in the gene associated with Mucopolysaccharidosis I (MPS I), Hurler Syndrome.

Turnaround Time

3 weeks

CPT Code(s)

81406

Cost

$1,000

Genes

  • IDUA

Clinical Information

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. Mucopolysaccharidosis type I (MPSI) is caused by deficient L-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

Molecular testing is useful to confirm the diagnosis and to identify the disease causing mutations within a family to allow for carrier testing and prenatal diagnosis.

Methodology

Sanger Sequencing

Detection

Sequencing of the gene will detect about 97% of abnormal alleles in individuals with a biochemical diagnosis.

Specimen Requirements

The preferred sample type is 3-5 ml of peripheral blood collected in an EDTA (purple top) tube. Extracted DNA, dried blood spots, and saliva are also accepted for this test. Saliva samples must be submitted in an approved saliva kit. Contact the lab to receive a saliva kit or to have one sent to your patient.

Transport Instructions

The specimen should be kept at room temperature and delivered via overnight shipping. If shipment is delayed by one or two days, the specimen should be refrigerated and shipped at room temperature. Do not freeze the specimen. Samples collected on Friday can be safely designated for Monday delivery.

Prenatal Testing Information

Prenatal diagnosis is available if the familial mutations are known. Additional fees for cell culture and maternal cell contamination may apply. Maternal cell contamination studies are required for all prenatal molecular tests. Contact the laboratory prior to sending a prenatal specimen.

Have Questions? Need Support?

Call our laboratory at 1-800-473-9411 or contact one of our Laboratory Genetic Counselors for assistance.
Robin Fletcher, MS, CGC
Falecia Thomas, MS, CGC
Alex Finley, MS, CGC

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