MMAB rs864309509: What Your Genotype Means
The rs864309509 variant is a rare genetic change located in the MMAB gene. It is associated with carrier status for methylmalonic aciduria type cblB, a condition that affects how the body processes vitamin B12.
What each genotype means
Typical genetic profile
This is the common, reference genotype for the MMAB gene at this location. It is not associated with the specific pathogenic condition described for this variant.
This is the most common genotype observed in the general population.
Carrier status
You carry one copy of the variant associated with methylmalonic aciduria type cblB. As a carrier, you typically do not exhibit symptoms of the condition, but you should discuss the implications of this result with a genetic counselor or healthcare provider.
This genotype is rare in the general population.
Increased risk profile
This genotype involves two copies of the variant associated with methylmalonic aciduria type cblB. This variant is classified as pathogenic in clinical databases, and you should consult with a medical professional to discuss what this means for your health.
This genotype is extremely rare in the general population.
Understanding the Variant
The variant rs864309509 is a specific change in the DNA sequence of the MMAB gene, which is located on chromosome 12. In genetics, a single nucleotide polymorphism (SNP) like this represents a variation at a single position in the genome. This particular variant is categorized as a rare genetic change. When researchers study such variants, they look at how the presence of a specific allele—the alternative version of the gene—might correlate with biological traits or health conditions. Because this variant is rare, it is not commonly found in the general population, and its presence is typically identified through targeted genetic testing or comprehensive genomic sequencing. Understanding where this variant sits in the MMAB gene is crucial, as the gene provides the blueprint for an enzyme that plays a vital role in cellular metabolism.
The Role of the MMAB Gene
The MMAB gene is responsible for producing an enzyme that is essential for the proper function of mitochondria, the energy-producing centers of our cells. This enzyme is involved in the formation of a compound called adenosylcobalamin (AdoCbl), which is a derivative of vitamin B12. AdoCbl is a necessary cofactor for another enzyme, methylmalonyl-CoA mutase. This mutase enzyme is responsible for breaking down certain proteins, fats, and cholesterol. When the MMAB gene is functioning normally, it ensures that the body can effectively process these nutrients. If the gene contains variants that disrupt the production or function of the MMAB enzyme, the body may struggle to create enough AdoCbl. This disruption can lead to the accumulation of toxic substances, such as methylmalonic acid, which can interfere with normal metabolic processes and lead to health challenges.
Research and Clinical Associations
Scientific research has linked variants in the MMAB gene to a condition known as methylmalonic aciduria type cblB. This is a metabolic disorder characterized by the body's inability to process vitamin B12 correctly. Individuals who are carriers of a pathogenic variant in this gene typically have one altered copy and one functional copy, which is usually sufficient to maintain normal metabolic function. However, if an individual inherits two altered copies—one from each parent—they may develop the clinical features of methylmalonic aciduria. The evidence for this association is considered moderate, as clinical outcomes can vary significantly depending on the specific nature of the genetic change. Research continues to explore how different mutations within the MMAB gene impact enzyme activity and overall health, helping clinicians better understand the spectrum of this condition.
Population Frequency and Interpretation
The rs864309509 variant is classified as rare, meaning it appears at a very low frequency across global populations. Because it is not a common variant, most people will not carry it. When interpreting genetic information, it is important to remember that being a carrier of a rare variant does not necessarily mean an individual will experience health symptoms. Genetic testing results should always be interpreted in the context of an individual's full medical history and family background. If you have received information about this variant, it is recommended to discuss the findings with a qualified healthcare provider or a genetic counselor. They can provide personalized context, explain the implications of carrier status, and help determine if any further clinical evaluation or family testing is appropriate for your specific situation.
How common is this variant?
The rs864309509 variant is considered rare in the general population, with its specific frequency varying by ancestry.
Frequently asked questions
What is methylmalonic aciduria type cblB?
It is a rare metabolic disorder caused by mutations in the MMAB gene that prevent the body from properly processing vitamin B12. This leads to the buildup of toxic compounds in the body.
Does having this variant mean I have a disease?
No, being a carrier of a single variant typically does not cause the disease. It simply means you carry one copy of an altered gene, which is usually managed by the other healthy copy.
Should I be worried about my vitamin B12 levels?
If you are concerned about your vitamin B12 levels or genetic status, you should consult with your doctor. They can order appropriate blood tests to check your metabolic health.
Can I change my genotype?
No, your genotype is determined at conception and cannot be changed. Genetic information is a static part of your biological makeup.
Sources & further reading
Educational information only, last refreshed 9/18/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Pathogenic variant in the MMAB gene associated with autosomal recessive methylmalonic aciduria type cblB.
This variant is associated with carrier status for methylmalonic aciduria type cblB.
This variant is associated with carrier status for methylmalonic aciduria type cblB.
This variant is identified as a carrier mutation for methylmalonic aciduria type cblB.