MMAB rs746219370: What Your Genotype Means
The rs746219370 variant is a genetic change located within the MMAB gene. It is associated with carrier status for methylmalonic aciduria type cblB, a rare inherited metabolic condition.
What each genotype means
Typical MMAB gene profile
This genotype represents the common, non-variant form of the MMAB gene at this position. Individuals with this profile do not carry this specific mutation associated with methylmalonic aciduria type cblB.
This is the most common genotype found in the general population.
Carrier of cblB mutation
This genotype indicates you are a carrier of a genetic variant in the MMAB gene associated with methylmalonic aciduria type cblB. Carriers are typically unaffected by the condition, as it is inherited in an autosomal recessive pattern, meaning it generally requires two copies of a pathogenic mutation to manifest symptoms.
This specific variant is rare in the general population.
Potential cblB variant homozygote
This genotype indicates the presence of two copies of the variant allele. Because this variant is classified as pathogenic for methylmalonic aciduria type cblB, individuals with this result should consult with a medical geneticist or healthcare provider to discuss clinical implications and potential health monitoring.
This genotype is extremely rare in the general population.
Understanding the Variant
The variant rs746219370 is a single nucleotide polymorphism (SNP) located on chromosome 12. In the context of human genetics, a SNP represents a variation at a single position in the DNA sequence. This specific variant is found within the MMAB gene, which provides the blueprint for an enzyme essential for cellular metabolism. When researchers identify this variant, they are looking at a specific 'letter' change in the genetic code that may alter how the body processes certain nutrients. Because this variant is rare, it is not typically included in standard health screenings unless specifically targeted. Understanding its location helps scientists study how variations in the MMAB gene might influence biological pathways, particularly those involving vitamin B12 processing within the mitochondria of our cells.
The Role of the MMAB Gene
The MMAB gene is responsible for producing an enzyme known as ATP:cob(I)alamin adenosyltransferase. This enzyme plays a critical role in the mitochondria, the energy-producing centers of our cells. Its primary job is to convert vitamin B12 into a functional coenzyme called adenosylcobalamin (AdoCbl). AdoCbl is necessary for the proper function of another enzyme, methylmalonyl-CoA mutase, which helps the body break down specific proteins, fats, and cholesterol. When the MMAB gene functions correctly, this metabolic pathway runs smoothly. However, if the gene contains certain pathogenic variants, the production of AdoCbl can be impaired. This disruption prevents the body from effectively breaking down these substances, which can lead to the accumulation of toxic compounds, a hallmark of methylmalonic acidemia.
Research and Clinical Significance
Research associates the rs746219370 variant with carrier status for methylmalonic aciduria type cblB. Methylmalonic aciduria is an autosomal recessive disorder, meaning that an individual typically needs to inherit two copies of a pathogenic variant—one from each parent—to manifest the condition. A carrier, by definition, has one functional copy of the gene and one variant copy, and they generally do not exhibit symptoms of the disease. The evidence strength for this association is considered moderate in clinical databases. It is important to note that the presence of this variant does not constitute a diagnosis of methylmalonic aciduria. Clinical diagnosis involves comprehensive metabolic testing, such as urine and plasma organic acid analysis, rather than genetic testing alone. If you have concerns about your carrier status, consult with a genetic counselor or a medical professional.
Population Frequency and Interpretation
The rs746219370 variant is classified as rare across human populations. Because it is not a common polymorphism, it is not frequently observed in large-scale genomic studies. When a variant is rare, its frequency can vary significantly between different ancestral groups, and data may be limited. In the context of genetic testing, finding this variant means you carry one copy of the altered gene. Because the condition is recessive, carriers are typically unaffected. However, if both parents are carriers of a pathogenic variant in the same gene, there is a 25% chance for each child to inherit two copies of the variant. This information is primarily used for family planning and understanding reproductive risks. It is not a tool for predicting personal health outcomes or diagnosing metabolic disorders.
How common is this variant?
The rs746219370 variant is considered rare in the general population. Specific frequency data across diverse ancestral groups remains limited due to its low prevalence.
Frequently asked questions
What does it mean to be a carrier for methylmalonic aciduria?
Being a carrier means you have one copy of a gene variant associated with the condition, but you typically do not show symptoms. Because the condition is autosomal recessive, you would generally need to inherit a second variant from the other parent to be at risk for the disease.
Does this variant mean I have methylmalonic aciduria?
No, identifying this variant does not mean you have the condition. Methylmalonic aciduria is a complex metabolic disorder diagnosed through clinical symptoms and biochemical testing, not solely by the presence of a single genetic variant.
Should I be worried if I have the C/T genotype?
The C/T genotype indicates you are a carrier. Carriers are typically healthy and do not experience symptoms of the condition. If you are concerned about family planning or reproductive risks, you should speak with a genetic counselor.
Is there a treatment for this variant?
There is no treatment for the variant itself, as it is simply a part of your genetic code. If an individual is diagnosed with methylmalonic aciduria, medical management often involves specialized diets and vitamin B12 supplementation under the strict supervision of a metabolic specialist.
Sources & further reading
Educational information only, last refreshed 9/19/2026. 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 identified as a carrier mutation for methylmalonic aciduria type cblB.
This variant is associated with carrier status for methylmalonic aciduria type cblB.