Ordering Recommendation

Carrier screening or diagnostic testing for maple syrup urine disease type 1B for individuals of Ashkenazi Jewish descent.




Polymerase Chain Reaction/Fluorescence Monitoring


Tue, Fri


5-10 days

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation

Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).

Specimen Preparation

Transport 3 mL whole blood. (Min: 1 mL)

Storage/Transport Temperature


Unacceptable Conditions

Plasma or serum. Specimens collected in sodium heparin or lithium heparin tubes. Frozen specimens in glass collection tubes.


Ambient: 72 hours; Refrigerated: 1 week; Frozen: 1 month

Reference Interval

By report

Interpretive Data

Background Information for Maple Syrup Urine Disease, Type 1B (BCKDHB), 3 Variants:
Characteristics: Maple syrup urine disease (MSUD), type 1B most commonly presents in the first few days of life. Symptoms include irritability, poor feeding, lethargy, intermittent apnea and typically progresses to coma and death within 7 to 10 days if untreated.
Incidence: 1 in 50,000 in Ashkenazi Jewish individuals.
Inheritance: Autosomal recessive.
Cause: BCKDHB pathogenic variants.
Variants Tested: p.R183P (c.548G>C), p.G278S (c.832G>A), p.E372X (c.1114G>T).
Clinical Sensitivity: 99 percent in Ashkenazi Jewish individuals; unknown in other ethnicities.
Methodology: Polymerase chain reaction (PCR) and fluorescence monitoring.
Analytical Sensitivity and Specificity: Greater than 99 percent.
Limitations: Variants other than those tested will not be detected. Diagnostic errors can occur due to rare sequence variations.

This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Compliance Category

Laboratory Developed Test (LDT)


Hotline History


CPT Codes



Component Test Code* Component Chart Name LOINC
2013731 Maple Syrup Urine Disease, Specimen
2013732 Maple Syrup Urine Disease, Allele 1
2013733 Maple Syrup Urine Disease, Allele 2
2013734 Maple Syrup Urine Disease, Interp
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.


  • MSUD
Maple Syrup Urine Disease, Type 1B (BCKDHB), 3 Variants