Maple syrup urine disease (MSUD) is a disorder caused by defects in the BCKAD enzyme complex that impairs the breakdown of specific amino acids (branched-chain amino acids) from the diet. The genetic cause for the type 1B form of MSUD is pathogenic variants in the BCKDHB gene.
MSUD1B is a rare disorder that affects 1 in 185,000 people in the general population. However, it is more common in people of Ashkenazi Jewish descent.
Take this test to find out if you are a genetic carrier for a BCKDHB variant and are at risk of passing it to your children.
MSUD1B is caused by variants in the BCKDHB gene. This gene provides instructions for the beta subunit of the BCKAD enzyme complex. The BCKAD complex is responsible for breaking down three branched-chain amino acids – leucine, isoleucine, and valine. The function of the BCKAD complex is impaired in affected individuals, resulting in an accumulation of these amino acids.
Maple syrup urine disease type 1B an autosomal recessive disorder, meaning that an individual must inherit two defective copies of the BCKDHB gene for symptoms to occur.
This test detects two genetic variants in the BCKDHB gene which occur in approximately 92% of carriers and affected people of Ashkenazi Jewish descent.
- rs28934895 C (R183P)
- rs386834233 A (G278S)
Understanding your carrier status for these variants will help you understand the risk of passing a variant to your children.
Affected infants show these symptoms:
- Sweet-smelling ear wax, urine and sweat
- Poor feeding
- High-pitched cry
- Spasms, involuntary muscle contractions, and an abnormal posture
- Developmental delays
If left untreated, affected children experience altered levels of consciousness (obtundation) leading to permanent brain damage, seizures, coma, and death.
How It Works
Step 1: Sign up for a free DNA Access account.
Step 2: Upload your DNA markers to DNA Access.
Step 3: Log in to your account to access your results when they are ready.