ENG rs121918401: Understanding Hereditary Hemorrhagic Telangiectasia
The rs121918401 variant is a rare, pathogenic genetic change located within the ENG gene. It is clinically associated with hereditary hemorrhagic telangiectasia (HHT), an autosomal dominant disorder characterized by abnormal blood vessel development.
What each genotype means
Typical ENG gene profile
This is the common, reference genotype for this position in the ENG gene. It is not associated with the pathogenic risks linked to the variant allele.
This is the most common genotype found in the general population.
Increased vascular malformation risk
This genotype includes one copy of the pathogenic variant associated with Hereditary Hemorrhagic Telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome. Individuals with this genotype should consult with a medical geneticist or specialist to discuss clinical implications and potential screening, as this condition can affect blood vessel development.
This genotype is very rare in the general population.
High vascular malformation risk
This genotype includes two copies of the pathogenic variant associated with Hereditary Hemorrhagic Telangiectasia (HHT). This condition is characterized by abnormal blood vessel formations that may lead to bleeding or other vascular complications; please discuss these findings with a healthcare provider for appropriate clinical evaluation.
This genotype is extremely rare in the general population.
What is the rs121918401 Variant?
The rs121918401 variant is a specific change in the DNA sequence of the ENG gene, which is located on chromosome 9. In genetic databases, this variant is categorized as a pathogenic mutation. This means that the presence of this specific alteration is known to disrupt the normal function of the gene, which can lead to clinical health consequences. Because it is a rare variant, it is not typically found in the general population at high frequencies. Genetic variants like rs121918401 are often identified through clinical genetic testing when individuals or families present with symptoms of vascular disorders. It is important to understand that this variant is a specific point of interest for researchers studying the molecular basis of vascular development and disease.
The Role of the ENG Gene
The ENG gene provides the essential instructions for producing a protein called endoglin. Endoglin is primarily found on the surface of cells that line the interior of blood vessels, particularly in developing arteries. This protein plays a critical role in the transforming growth factor-beta (TGF-beta) signaling pathway, which is vital for the proper formation and stabilization of blood vessels. By forming complexes with other proteins, endoglin helps regulate how blood vessels specialize into arteries or veins. When the ENG gene is mutated, the resulting endoglin protein may be non-functional or absent, which impairs the body's ability to maintain the structural integrity of the vascular system. This disruption is the underlying cause of hereditary hemorrhagic telangiectasia type 1 (HHT1).
Research and Clinical Associations
Research has firmly established a link between pathogenic variants in the ENG gene and hereditary hemorrhagic telangiectasia (HHT). HHT is an autosomal dominant condition, meaning that inheriting a single copy of a pathogenic variant from one parent is sufficient to cause the disorder. Clinical manifestations of HHT include telangiectases—small, fragile vascular lesions often found on the lips, nose, and fingers—as well as larger arteriovenous malformations (AVMs) in organs such as the lungs, liver, and brain. The evidence for the pathogenicity of variants in this gene is strong, supported by clinical genetic panels and expert curation. While the association between ENG mutations and HHT is well-documented, the specific clinical severity can vary between individuals, even within the same family, due to other genetic and environmental factors.
Population Frequency and Interpretation
The rs121918401 variant is considered very rare in the general population. Because it is a pathogenic variant associated with a specific medical condition, it is not a common polymorphism found in the general public. Most individuals do not carry this variant. When it is identified, it is usually in the context of a clinical diagnostic workup for patients exhibiting symptoms of HHT or in family members of someone already diagnosed with the condition. Because of its rarity, population-wide frequency data is limited, and the variant is primarily tracked in clinical databases like ClinVar. It is not a variant that would typically be reported in routine, non-clinical genetic screening.
What You Can Do With This Information
If you have received information regarding the rs121918401 variant, it is essential to consult with a qualified healthcare professional, such as a genetic counselor or a medical geneticist. This information is for educational purposes and should not be used for self-diagnosis or to make medical decisions. A clinician can help interpret what this result means for your health and provide guidance on appropriate screening or management strategies if necessary. If you are concerned about a family history of vascular issues or HHT, a clinical evaluation is the most reliable way to assess your risk. Never attempt to diagnose yourself based on genetic data; always discuss your findings with a medical expert who can place the information in the context of your personal and family health history.
How common is this variant?
The rs121918401 variant is extremely rare in the general population, as it is a pathogenic mutation associated with a specific hereditary vascular disorder.
Frequently asked questions
What is hereditary hemorrhagic telangiectasia (HHT)?
HHT is a genetic disorder that causes abnormal blood vessel formation, leading to fragile vessels that can bleed easily. It often results in nosebleeds, skin lesions, and internal vascular malformations.
Is rs121918401 a common genetic variant?
No, this variant is very rare. It is not a common polymorphism found in the general population and is typically only identified in clinical settings.
Can I use this information to diagnose myself?
No. Genetic information should only be interpreted by a qualified healthcare professional. You should discuss any genetic findings with a doctor or genetic counselor.
What should I do if I have this variant?
If you have been identified as a carrier of this variant, you should consult with a medical geneticist or a specialist familiar with HHT. They can provide appropriate clinical follow-up and family screening.
Does having this variant guarantee I will have symptoms?
HHT is an autosomal dominant condition, but the severity and specific symptoms can vary significantly between individuals. A clinician can help assess your specific clinical risk.
Sources & further reading
Educational information only, last refreshed 10/7/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Genetic variant identified in the ENG gene, relevant for clinical screening of vascular disorders.
Pathogenic variant in the ENG gene associated with hereditary hemorrhagic telangiectasia type 1.
A variant in the ENG gene potentially impacting protein function related to vascular development.
This variant is located within the ENG gene, which is associated with hereditary hemorrhagic telangiectasia.
Clinically significant variant in the ENG gene associated with hereditary hemorrhagic telangiectasia.
This ENG variant is documented in clinical databases regarding vascular health.