PMM2 rs398123310: Understanding This Rare Genetic Variant
The rs398123310 variant is a rare genetic change located within the PMM2 gene. It is associated with PMM2-CDG, a condition involving the body's ability to process glycoproteins, which can lead to distinct physical and neurological features.
What each genotype means
Typical PMM2 gene profile
This is the most common genotype observed in the general population for this location in the PMM2 gene. It is considered the reference sequence and is not associated with the metabolic conditions linked to this variant.
This is the most frequent genotype found across all global populations.
Carrier of rare variant
You carry one copy of the G allele, which is a rare genetic change in the PMM2 gene. While this variant is classified as potentially pathogenic in clinical databases, carrying a single copy typically does not cause the metabolic condition known as PMM2-CDG, which generally requires two copies of a pathogenic variant.
This genotype is rare and observed at a very low frequency in the general population.
Potential metabolic risk profile
This genotype involves two copies of the G allele, which has been identified in clinical databases as potentially pathogenic and linked to PMM2-congenital disorder of glycosylation (PMM2-CDG). This condition is a rare metabolic disorder that can affect multiple organ systems, and you should discuss these findings with a medical geneticist or healthcare provider to understand the clinical implications for your health.
This genotype is extremely rare in the general population.
What is rs398123310?
The variant rs398123310 is a specific change in the DNA sequence of the PMM2 gene, which is located on chromosome 16. In genetics, a single nucleotide polymorphism (SNP) like this represents a variation at a single position in the genome. While most variations in our DNA are common and have little to no impact on our health, some are rare and can alter the function of the proteins our bodies produce. This particular variant is categorized as rare, meaning it is not found in the vast majority of the human population. Researchers track these variants to understand how they might contribute to specific biological traits or health conditions. Because it is located within a gene that provides instructions for a critical enzyme, scientists pay close attention to how this specific change might affect the enzyme's stability or activity levels within the cell.
The Role of the PMM2 Gene
The PMM2 gene provides the blueprint for an enzyme called phosphomannomutase 2. This enzyme plays a vital role in a process known as glycosylation, where sugar molecules are attached to proteins. Glycosylation is essential for the proper structure and function of many proteins throughout the body. When the PMM2 gene contains certain variants, the resulting enzyme may not function correctly, leading to a group of conditions known as Congenital Disorders of Glycosylation (CDG). Specifically, PMM2-CDG is the most common type of these disorders. Because glycosylation is a fundamental process, disruptions can manifest in various ways, including neurological symptoms and distinct physical characteristics. Understanding the function of PMM2 helps researchers explain why specific genetic changes can lead to such a wide spectrum of clinical presentations in affected individuals.
Research and Clinical Significance
Clinical databases, such as ClinVar, have annotated rs398123310 as potentially pathogenic. This classification suggests that the variant has been linked to PMM2-CDG in clinical settings. However, it is important to note that the evidence strength for this specific variant is considered moderate. In the field of genomics, 'pathogenic' means the variant is likely to contribute to a disease, but the clinical expression can vary significantly between individuals. Research into this variant often involves studying family histories and the biochemical impact on enzyme activity. Because this is a rare variant, much of the current knowledge is derived from clinical case studies rather than large-scale population-wide association studies. As more data is collected in global databases like gnomAD, our understanding of the variant's true impact and its penetrance—how often it actually causes symptoms—continues to evolve.
Interpreting Your Genetic Information
If you encounter this variant in a genetic report, it is essential to understand that genetic information is complex and should not be used for self-diagnosis. A variant being 'potentially pathogenic' does not guarantee that an individual will experience specific health issues, as many factors, including other genetic modifiers and environmental influences, play a role. If you have concerns about a genetic finding, the most appropriate step is to consult with a qualified healthcare provider or a genetic counselor. They can help place the information in the context of your personal and family medical history. You cannot 'fix' or 'change' a genetic variant, but professional guidance can help you understand what the information means for your health and whether any clinical follow-up is necessary. Always rely on clinical testing ordered by a professional rather than direct-to-consumer reports for medical decision-making.
How common is this variant?
The rs398123310 variant is considered rare across all major ancestral populations, appearing at very low frequencies in global genomic databases.
Frequently asked questions
What is PMM2-CDG?
PMM2-CDG is a rare genetic disorder caused by mutations in the PMM2 gene that affect the body's ability to attach sugar molecules to proteins. This process, called glycosylation, is essential for many bodily functions, and its disruption can lead to neurological and physical symptoms.
Is rs398123310 a diagnosis?
No, identifying a genetic variant is not a medical diagnosis. Genetic variants are only one piece of a larger puzzle, and a clinical diagnosis requires a comprehensive evaluation by a medical professional, including physical exams and biochemical testing.
Should I be worried if I have this variant?
Finding a rare variant does not necessarily mean you will develop a condition. You should discuss any genetic findings with a doctor or a genetic counselor who can interpret the results based on your specific health history.
Where can I learn more about PMM2?
You can find reliable information about the PMM2 gene and related disorders through resources like MedlinePlus Genetics, the National Organization for Rare Disorders (NORD), and the NCBI Gene database.
Sources & further reading
Educational information only, last refreshed 9/30/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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