HBB Gene and Sickle Cell Disease: Mutations and Clinical Trials
The HBB gene sits on chromosome 11p15.4, and its full name is hemoglobin subunit beta. Orphanet links HBB to 28 rare conditions and lists variants in the gene as a cause of 26 of them. Trial Friend's Sickle Cell Disease and Thalassemia pages list HBB among the genes behind each condition. As of September 29, 2026, no recruiting or soon-opening trial on ClinicalTrials.gov names HBB as a gene. The condition pages below list every open trial for those conditions.
Other symbols for HBB in gene databases: CD113t-C.
What the HBB gene does
HBB makes beta-globin, one of the building blocks of hemoglobin, the protein in red blood cells that carries oxygen from the lungs to the rest of the body. Adult hemoglobin usually has 2 beta-globin and 2 alpha-globin units.
Summarized from the HBB page on MedlinePlus Genetics, U.S. National Library of Medicine, checked September 29, 2026.
Conditions linked to HBB on Trial Friend
These condition pages list HBB among the genes behind the condition, checked against genetics references when each page was written.
The condition usually appears only when both copies of the gene carry a disease-causing variant. One variant alone usually means a person is a carrier.
HbSS is homozygous for the sickle HBB variant; HbSC and HbS-beta-thalassemia combine it with another HBB variant.
The condition usually appears only when both copies of the gene carry a disease-causing variant. One variant alone usually means a person is a carrier.
Beta thalassemia is HBB; alpha thalassemia is usually deletion of one to four HBA1/HBA2 alleles, so testing must include deletion analysis.
HBB mutation clinical trials
These recruiting or soon-opening trials mention HBB as a gene in their title, summary, eligibility rules or keywords. Some want people with a variant in it, and others study it more broadly, which is why each trial's own words are shown. In cancer trials the gene change is usually one found in the tumor rather than one a person inherited.
As of September 29, 2026, no recruiting or soon-opening trial on ClinicalTrials.gov names HBB as a gene. The condition pages above list every open trial for those conditions.
All conditions linked to HBB gene mutations
Orphanet records how each gene relates to each condition. Orphanet links HBB to 28 rare conditions and lists variants in the gene as a cause of 26 of them.
- Causes it. Disease-causing variants in this gene are a direct cause of the condition.
- Fusion gene. The gene is part of an abnormal fusion found in the tumor, not usually inherited.
HBB genetic test results and what a variant can mean
Labs sort each variant they find into 5 groups, from pathogenic and likely pathogenic through uncertain significance to likely benign and benign. Only the first 2 are usually treated as the cause of a condition. A variant of uncertain significance, or VUS, is one without enough evidence either way yet, and labs can reclassify it as research builds.
A genetic counselor or your doctor can explain what a specific result means for you and your family. Our genetic testing guide covers the terms, and MedlinePlus Genetics from the National Library of Medicine has a plain-language page on HBB.
HBB gene questions
What does the HBB gene do?
HBB makes beta-globin, one of the building blocks of hemoglobin, the protein in red blood cells that carries oxygen from the lungs to the rest of the body. Adult hemoglobin usually has 2 beta-globin and 2 alpha-globin units. This summary follows MedlinePlus Genetics from the U.S. National Library of Medicine.
Are there clinical trials for people with HBB gene variants?
As of September 29, 2026, no recruiting or soon-opening trial on ClinicalTrials.gov names HBB as a gene. ClinicalTrials.gov also lists 213 open trials for Sickle Cell Disease and 92 for Thalassemia, and Match Me on Trial Friend can check those against age, sex, location and treatment history.
What conditions are linked to the HBB gene?
Orphanet links HBB to 28 rare conditions and lists variants in the gene as a cause of 26 of them. They include Beta-thalassemia intermedia, Beta-thalassemia major, Delta-beta-thalassemia, Hemoglobin C-beta-thalassemia syndrome, Hemoglobin E-beta-thalassemia intermedia, Hemoglobin E-beta-thalassemia major and 22 more. Orphanet is the European rare disease database run by INSERM in Paris.
How is Sickle Cell Disease inherited?
The inheritance pattern is autosomal recessive. The condition usually appears only when both copies of the gene carry a disease-causing variant. One variant alone usually means a person is a carrier. HbSS is homozygous for the sickle HBB variant; HbSC and HbS-beta-thalassemia combine it with another HBB variant.
How is Thalassemia inherited?
The inheritance pattern is autosomal recessive. The condition usually appears only when both copies of the gene carry a disease-causing variant. One variant alone usually means a person is a carrier. Beta thalassemia is HBB; alpha thalassemia is usually deletion of one to four HBA1/HBA2 alleles, so testing must include deletion analysis.
What does an HBB variant of uncertain significance mean?
A variant of uncertain significance, or VUS, is a change in the gene that labs don't yet have enough evidence to call disease-causing or harmless. It is not used on its own to diagnose a condition, and labs can reclassify it as research builds. A genetic counselor can explain what a specific result means for you and your family.
Sources
- Gene and condition links from Orphadata (Orphanet, INSERM US14), used under CC BY 4.0, read September 29, 2026.
- Trials from ClinicalTrials.gov, read September 29, 2026.
- HBB gene, MedlinePlus Genetics, U.S. National Library of Medicine.
- Inheritance and gene notes from the Trial Friend condition pages above, each checked against genetics references.
Other gene pages
The gene search covers every gene Orphanet links to a rare disease.