Maple Syrup Urine Disease (MSUD) Mutation Analysis

CPT 81205
Synonyms BCKD Deficiency; Branched-chain Ketoaciduria; Jewish Heritage Test; MSUD Carrier Testing, DNA;

Test Details

Turnaround Time

7 - 15 days (If cultured cells are needed, an additional 7-12 days may be required. Additional culture fee may be included.) Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Special Instructions

Prenatal testing: Integrated Genetics clients should call 800-848-4436 to speak to a laboratory genetic coordinator before collecting any specimens. In some circumstances, specimens from other family members may be required. All prenatal specimens (including cord blood) must be accompanied by a maternal blood or mouthwash specimen for analysis of possible maternal cell contamination. Discard first 2 mL; then 10 mL amniotic fluid in 15 mL orange-top polypropylene tube, 10-15 mg chorionic villi in laboratory-provided screw-top tubes with sterile transport medium or one T-25 flask of confluent cells. Additional sample must be obtained for back-up culture at one of our cytogenetics laboratories or another facility. If additional testing is desired, more amniotic fluid is needed. For example, chromosome analysis requires an additional 15-25 mL (see Cytogenetics – Amniotic Fluid Chromosome Analysis test page) and AFAFP requires an additional 2 mL (see Amniotic Fluid Alpha-Fetoprotein - AFAFP test page).

Test Includes

Mutation(s) include: c.1312T>A (p.Y438N) (legacy name: Y438N (Y393N)); c.548G>C (p.R183P); c.832G>A (p.G278S); c.1114G>T (p.E372*) (legacy name: E372X (E422X))


False positive or false negative results may occur for reasons that include: genetic variants, technical handling, blood transfusions, bone marrow transplantation, mislabeling of samples, or erroneous representation of family relationships.


Polymerase chain reaction (PCR); primer extension; flow-sorted bead array analysis

Additional Information

Couples who are planning a pregnancy or who are already pregnant may decide to have testing to find out if they are carriers and at risk of having a baby with MSUD. If both parents are found to be carriers, prenatal diagnosis by CVS or amniocentesis is available. Indications for MSUD testing include: Individuals with clinical characteristics of MSUD or family history of MSUD. Our MSUD analysis tests for 4 mutations for a 99% carrier detection rate in the Ashkenazi Jewish population.

Specimen Requirements

Information on collection, storage, and volume


Whole blood or mouthwash (see specimen kit for detailed instructions), amniotic fluid, chorionic villi.


Postnatal: 10 mL whole blood or mouthwash / Prenatal: 10mL amniotic fluid in orange-top polypropylene tube, 10-15 mg chorionic villi in laboratory provided screw-top tubes with sterile transport medium or one T-25 flask of confluent cells.


Lavender-top (EDTA) tube or yellow-top (ACD-A) tube or mouthwash kit

Storage Instructions

Maintain specimen at room temperature

Causes for Rejection

Frozen specimen; hemolysis; quantity not sufficient for analysis; improper container; unlabeled or mislabeled specimen


Mouthwash collection: Patient should not eat, drink, smoke or chew gum for at least one hour prior to collection. (See specimen kit for detailed instructions). Mouthwash samples can be sent when ordering up to two tests. When ordering more than two tests, blood samples are required. 10 mL of Scope® mouthwash that has been swished vigorously for at least 1 minute. Collect in orange-top 50 mL polypropylene tube.