BCKDHB rs113994152: What Your Genotype Means
The rs113994152 variant in the BCKDHB gene is a specific genetic change known as p.Arg183Pro. It is recognized as a pathogenic variant associated with Maple Syrup Urine Disease (MSUD) type 1B, a rare metabolic disorder.
What each genotype means
Typical enzyme function
This genotype represents the most common genetic sequence at this location in the BCKDHB gene. It is not associated with the specific pathogenic variant linked to Maple Syrup Urine Disease (MSUD) type 1B.
This is the most common genotype found in the general population across all ancestries.
Carrier status
You carry one copy of the p.Arg183Pro variant, which is associated with Maple Syrup Urine Disease (MSUD) type 1B. As this condition is inherited in an autosomal recessive manner, carrying a single copy typically does not cause symptoms, but you may pass this variant to your children.
This genotype is rare, with an allele frequency of approximately 0.005 in the Ashkenazi Jewish population and lower frequencies in other groups.
Potential MSUD risk
This genotype indicates the presence of two copies of the p.Arg183Pro variant. Research identifies this variant as pathogenic and causative of Maple Syrup Urine Disease (MSUD) type 1B, a condition that affects the body's ability to break down certain amino acids.
This genotype is extremely rare in the general population.
Understanding the Variant
The variant rs113994152, often referred to as c.548G>C or p.Arg183Pro, is a single nucleotide polymorphism located within the BCKDHB gene. This gene provides the instructions for creating the beta subunit of the branched-chain alpha-keto acid dehydrogenase (BCKD) enzyme complex. In this specific variant, a single DNA building block is altered, which results in the substitution of the amino acid arginine with proline at position 183 of the protein. This change can affect the structural integrity or function of the resulting enzyme. Because this variant is located in a gene critical for metabolic processes, it is categorized as a pathogenic variant in clinical databases, meaning it is known to contribute to the development of specific health conditions when inherited in a particular manner.
The Role of the BCKDHB Gene
The BCKDHB gene is essential for the body's ability to break down certain amino acids—leucine, isoleucine, and valine—which are found in protein-rich foods like meat, eggs, and milk. The BCKD enzyme complex acts like a biological machine that processes these amino acids so they can be used for energy or other cellular functions. When the BCKDHB gene contains a pathogenic mutation, the enzyme complex may not function correctly. This leads to a buildup of these amino acids and their toxic byproducts in the body. This accumulation is the hallmark of Maple Syrup Urine Disease (MSUD), a condition named for the sweet, maple-syrup-like odor often detected in the urine of affected infants. If left unmanaged, this buildup can cause serious health issues, including neurological problems.
Research and Clinical Evidence
The evidence linking rs113994152 to MSUD type 1B is well-documented in clinical genetics literature. It is considered a founder mutation, meaning it is more frequently observed in specific ancestral groups, such as the Ashkenazi Jewish population. Clinical databases like ClinVar classify this variant as pathogenic, as it has been identified in individuals diagnosed with MSUD. MSUD is an autosomal recessive condition, which means that an individual typically needs to inherit two copies of a pathogenic variant—one from each parent—to manifest the disease. While this variant is a known cause of the condition, the severity of symptoms can vary between individuals. Genetic testing for this variant is often included in expanded carrier screening panels to help individuals understand their risk of passing the condition to their children.
Population Frequency
The frequency of the rs113994152 variant varies significantly across different global populations. It is most notably recognized as a founder mutation within the Ashkenazi Jewish population, where the allele frequency is approximately 0.005. Because it is a rare variant, it is not commonly found in the general global population. Understanding these frequency differences is important for genetic counseling, as it helps clinicians determine which populations might benefit most from targeted screening. If you have received results indicating you are a carrier for this variant, it simply means you have one copy of the altered gene. Carriers typically do not show symptoms of MSUD, but they may want to discuss the implications of this result with a genetic counselor or a medical professional, especially when planning a family.
What This Information Means for You
If you have identified this variant in your genetic data, it is important to remember that this is not a medical diagnosis. Genetic information is complex, and the presence of a single variant does not necessarily predict a health outcome. For recessive conditions like MSUD, being a carrier is common and generally does not affect your own health. However, if you are concerned about your carrier status or family planning, the best course of action is to consult with a board-certified genetic counselor. They can provide context based on your full genetic profile and family history. Never make changes to your diet or medical care based on genetic reports without first speaking to a qualified healthcare provider who can interpret these findings in the context of your overall health.
How common is this variant?
The rs113994152 variant is a founder mutation in the Ashkenazi Jewish population with an allele frequency of approximately 0.005.
Frequently asked questions
What is Maple Syrup Urine Disease?
Maple Syrup Urine Disease (MSUD) is a rare, inherited metabolic disorder where the body cannot properly break down certain amino acids. This leads to a buildup of toxic substances that can cause serious health issues if not managed.
Does having this variant mean I have MSUD?
Not necessarily. MSUD is an autosomal recessive condition, meaning it usually requires two copies of a pathogenic variant to cause the disease. Being a carrier (having one copy) typically does not cause symptoms.
Should I change my diet if I am a carrier?
No. Carriers of recessive conditions like MSUD do not typically require dietary changes. Always consult with a doctor or a registered dietitian before making any changes to your diet based on genetic information.
What should I do if my report says I am a carrier?
If you are a carrier, you may want to speak with a genetic counselor. They can explain what this means for your health and your family planning options.
Is this variant common?
This variant is rare in the general population but is more common in the Ashkenazi Jewish population due to a founder effect. It is not a common variant found in most people.
Sources & further reading
Educational information only, last refreshed 9/27/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Pathogenic missense mutation (p.Arg183Pro) in BCKDHB causing maple syrup urine disease type 1B.
A missense variant (c.548A>G, p.Asn183Ser) in BCKDHB causing classic Maple Syrup Urine Disease (MSUD) type 1B in homozygotes and defining Ashkenazi Jewish carrier status.
Pathogenic variant (c.827T>G; p.Arg276Gly) associated with maple syrup urine disease type 1B.
This variant in the BCKDHB gene is linked to Maple Syrup Urine Disease and is documented in clinical variant databases.