HBB rs33945705: Understanding Hemoglobin Variants
The rs33945705 variant is a rare genetic change located within the HBB gene, which provides instructions for making beta-globin. This variant is associated with specific hemoglobin types that can alter the structure and function of red blood cells.
What each genotype means
Typical hemoglobin profile
This genotype represents the common, reference sequence for this position in the HBB gene. It is not associated with the specific hemoglobin variants linked to this rsID.
This is the most common genotype observed in general populations.
Carrier of hemoglobin variant
You carry one copy of the reference allele and one copy of the A allele, which is associated with specific hemoglobin variants like Hemoglobin Vancouver or Hemoglobin Ziguinchor. Because this is a rare variant, clinical implications for carriers are limited and should be discussed with a medical professional if you have concerns about blood health.
This genotype is rare in the general population.
Carrier of hemoglobin variant
You carry one copy of the reference allele and one copy of the T allele, which is associated with hemoglobin variants such as Hemoglobin Korle-Bu. As this is a rare variant, its specific impact on your health is not well-defined in general population studies; consult a clinician for personalized medical context.
This genotype is rare in the general population.
Hemoglobin variant carrier
This genotype indicates the presence of the A allele, which is linked to specific hemoglobin variants. Research on this rare variant is limited, and its clinical significance for an individual is not fully established; please consult with a healthcare provider for any relevant medical evaluation.
This genotype is extremely rare.
Hemoglobin variant carrier
This genotype indicates the presence of the T allele, which is linked to specific hemoglobin variants. Research on this rare variant is limited, and its clinical significance for an individual is not fully established; please consult with a healthcare provider for any relevant medical evaluation.
This genotype is extremely rare.
What is rs33945705?
The rs33945705 variant is a single nucleotide polymorphism (SNP) located on chromosome 11 within the HBB gene. In genetic databases, it is often identified by its position on the genome and its association with specific structural changes in the hemoglobin protein. Unlike common variants that might influence height or eye color, this SNP is categorized as a rare variant. It represents a specific change in the DNA sequence that can lead to the production of altered beta-globin subunits. Because it sits within the HBB gene, any change here has the potential to affect how hemoglobin molecules assemble and function within red blood cells. Researchers track such variants to understand how minor shifts in the genetic code can result in different hemoglobin variants, which are sometimes named after the locations where they were first identified or studied.
The Role of the HBB Gene
The HBB gene is responsible for producing beta-globin, a critical protein subunit that combines with other components to form hemoglobin. Hemoglobin is the iron-rich protein inside red blood cells that carries oxygen from the lungs to the rest of the body. When the HBB gene functions normally, it ensures that hemoglobin is produced in the correct amount and structure to maintain efficient oxygen delivery. However, because hemoglobin is a complex molecule, even small changes in the HBB gene can alter its shape or stability. These alterations can impact the red blood cell's ability to hold or release oxygen effectively. While many HBB variants are well-known for causing conditions like sickle cell disease or beta-thalassemia, others, like those associated with rs33945705, result in specific hemoglobin variants that may have different clinical implications depending on the individual's overall genetic background.
Research and Clinical Associations
Scientific literature associates rs33945705 with the production of specific hemoglobin variants, including Hemoglobin Vancouver, Hemoglobin Ziguinchor, and Hemoglobin Korle-Bu. These are structural variants where the amino acid sequence of the beta-globin protein is changed, potentially affecting the protein's stability or its affinity for oxygen. The evidence linking this specific SNP to these conditions is documented in clinical databases like ClinVar, where it is noted for its role in these rare hemoglobinopathies. It is important to note that the clinical impact of these variants can vary significantly between individuals. While some hemoglobin variants are benign and cause no symptoms, others may lead to hematological changes that require medical monitoring. Because the evidence for this specific variant is limited, it is not typically used for routine health screening, and its presence does not automatically imply a specific health outcome.
Population Frequency
The rs33945705 variant is considered rare in the general population. Because it is not a common polymorphism, it is not frequently observed in large-scale genomic studies of diverse ancestral groups. Its rarity means that most individuals do not carry this variant, and it is typically identified only in specific clinical contexts or research studies focusing on hemoglobin disorders.
Managing Genetic Information
If you have received information about this variant through genetic testing, it is essential to understand that this data is for educational purposes and does not constitute a medical diagnosis. Genetic variants in the HBB gene can have complex effects, and their clinical significance often depends on whether they are inherited from one or both parents, as well as the presence of other genetic factors. You cannot use this information to self-diagnose or make decisions about your health. If you are concerned about your hemoglobin levels or potential genetic conditions, the most appropriate step is to consult with a healthcare provider or a genetic counselor. They can interpret your results in the context of your personal and family medical history and recommend appropriate clinical testing if necessary. Always discuss any findings related to blood health with a qualified medical professional.
How common is this variant?
The rs33945705 variant is rare across all major population groups, appearing infrequently in global genomic databases.
Frequently asked questions
What does it mean to have a rare HBB variant?
A rare HBB variant means that the specific DNA sequence change is not common in the general population. While some HBB variants cause well-known blood disorders, many others are rare and may have unknown or mild effects on health.
Can this variant affect my physical performance?
Some hemoglobin variants can theoretically impact how oxygen is delivered to tissues, which is vital for physical performance. However, there is no evidence that this specific variant significantly alters performance in the general population.
Should I be worried if I have this variant?
Finding a rare variant does not necessarily mean you have a health problem. You should discuss the result with a doctor or genetic counselor who can evaluate it alongside your actual blood test results and medical history.
Is this the same as sickle cell trait?
No, this variant is distinct from the specific mutation that causes sickle cell disease. While both involve the HBB gene, they represent different changes in the DNA sequence.
Sources & further reading
Educational information only, last refreshed 9/22/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Classic beta-globin missense variant (p.Glu7Lys, HbC; historically Glu6Lys) conferring hemoglobin C disease and substantial protection against severe Plasmodium falciparum malaria.
Beta-globin coding variant causing Hemoglobin C (p.Glu7Lys), which confers partial resistance to malaria but predisposes homozygous carriers to mild chronic hemolytic anemia.
This variant is associated with Hemoglobin Coimbra, a condition that can impact systemic health and potentially influence ocular oxygenation.
Causes Hemoglobin S-Antilles, an ancestral structural beta-globin mutation conferring altered oxygen affinity and sickle cell pathology under low oxygen tension.
Pathogenic nonsense mutation (c.118C>T / p.Gln40Ter / codon 39 nonsense) causing beta-zero thalassemia and classic carrier status (beta-thalassemia minor).
Encodes Hemoglobin C-Harlem, an ancestral double-mutation variant conferring sickle-beta-thalassemia-like phenotypes in descendants of African lineages.