Maple syrup urine disease carrier test, DNA

Alphabetical Test listing

Maple syrup urine disease carrier test, DNA-13563

  
Maple syrup urine disease carrier test, DNA
  
13563
  
LAB13563
  
MAPSU
  
BCKD deficiency
Branched-chain ketoaciduria
Jewish heritage test
Maple syrup urine disease
MSUD carrier testing, DNA
  

Carrier screening for Maple syrup urine disease (MSUD, OMIM 248600), an inherited recessive disease caused by deficient activity of branched-chain alpha-ketoacid dehydrogenase.

DNA testing is appropriate for carrier screening and confirmation of mutations in individuals from specific ethnic groups (see Limitations).

  
EDTA whole blood
  
  
7.0 mL
  
3.0 mL
  

Lavender (EDTA), 10mL

  
ACD whole blood
Amniotic fluid
Chorionic villus sample (CVS) (submission of maternal blood is required for fetal testing)
  

Yellow ACD (A or B)

 

Sterile vial/container

 

 

  
ACD whole blood - 7 mL (minimum 3 mL)
Amniotic fluid - 10 mL (minimum 5 mL)
Chorionic villus sample (CVS) - 20 mg (minimum 10 mg)
  

Yellow ACD (A or B)

Sterile vial/container

  

Ambient

Refrigerated

  
  • Frozen specimen
  • Hemolysis
  • Quantity not sufficient for analysis (QNS)
  • Improper container
  
LabCorp RTP (511310): R-LC
  
Two (2) times per week, or as needed
  
7 - 15 days
If cultured cells are needed, an additional 7-12 days may be required
  

Polymerase chain reaction (PCR) and primer extension

  

An interpretive report will be provided

  

DNA testing is appropriate for carrier screening in individuals of Ashkenazi Jewish or Mennonite ancestry, confirmation of mutations in patients previously diagnosed with MSUD who belong to these ethnic groups, and prenatal diagnosis for at-risk couples who are known to carry the mutations detected by this test.

MSUD can be detected by newborn screening and effectively treated with dietary restriction. Almost all state newborn screening programs are required by statute to screen infants for MSUD. Untreated disease is characterized by poor feeding, brain damage, and ultimately coma and death. Even with dietary restriction of branched-chain amino acids, affected individuals may still have periodic metabolic crises due to infection or stress. Impaired intellectual development or neurological complications can occur if the initial diagnosis is delayed.  The disease is present inall ethnic groups, but has elevated prevalence among Ashkenazi Jews and Mennonites.  Parents who are each carriers of MSUD are asymptomatic, but have a 25% chance with each pregnancy to have a child with the disease. Prenatal diagnosis can be performed by molecular mutation analysis (when the mutations in the family are known) or by measurement of enzyme activity in amniocytes. Molecular testing for MSUD encompasses four mutations in two components of the branched-chain ketoacid dehydrogenase complex (BCKAD): the E1 alpha-subunit (BCKDHA, OMIM 608438), and the E1 beta-subunit (BCKDHB, OMIM 248611). Plasma amino acid analysis can be used to diagnose affected individuals, but cannot determine carrier status. A negative result of this DNA test in an individual of Ashkenazi Jewish or Mennonite ancestry decreases the likelihood that a person is a carrier, but cannot completely eliminate the possibility. The presence of a rare mutation cannot be ruled out. DNA test results must be combined with clinical and family history information for the most accurate interpretation.

  
81205
  
Yes
  
  
Result 53039-4
  
04/10/2019
  
05/20/2019
  
03/09/2021