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Screening for Alpha Thalassemia in Healthy Volunteers

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Know the risks and potential benefits of clinical studies and talk to your health care provider before participating. Read our disclaimer for details.
ClinicalTrials.gov Identifier: NCT02692872
Recruitment Status : Recruiting
First Posted : February 26, 2016
Last Update Posted : January 27, 2023
Information provided by (Responsible Party):
National Institutes of Health Clinical Center (CC) ( National Institute of Allergy and Infectious Diseases (NIAID) )

Brief Summary:


Alpha thalassemia is a blood disorder. It is caused by genetic deletions. Part of the DNA is missing from a group of genes called alpha globin. Alpha thalassemias are some of the most common genetic deletions. We are testing for alpha thalassemia trait. Alpha thalassemia trait is when someone has only two out of the normal four alpha globin genes. In some people, they lead to no symptoms. Others have changes that lead to disease, including mild anemia. Researchers want to learn more about alpha thalassemia and blood vessels. This may allow them to develop new treatments for blood diseases such as sickle cell disease.


To better understand how alpha globin deletions in healthy people affect blood vessels.


Healthy volunteers ages 18-39 who self-report African ancestry.


Participants will provide a one-time saliva sample. This can be by mail, in-person at a study event, or at NIH.

Participants will get a small kit to collect their saliva sample. The kit has easy instructions. The sample does not need to be put in the refrigerator.

Participants will spit a small amount of saliva (less than half a teaspoon) into a collection tube.

Participants will close the funnel lid tightly, and then unscrew the funnel lid from the tube. They will then close the tube tightly with the small cap provided and shake the tube for 5 seconds.

Participants will place the tube in the provided envelope and mail it to NIH. The specimen will be stored and processed in the lab.

Participants may be invited to participate in more research studies, whether or not researchers find that they have alpha thalassemia trait.

Condition or disease
Alpha Thalassemia

Detailed Description:

Many of the complications of sickle cell disease, such as stroke, kidney damage, skin ulceration,pulmonary hypertension, and cardiac hypertrophy are prevented, delayed or reduced by inheritance of one of more deletions of the alpha globin genes. Our long-term research goal is to understand how deletions of alpha globin protect against the vascular complications of sickle cell disease.

Deletions of alpha globin are common and found in approximately 5% of the world s population.They are especially common among Africans and people of African ancestry, as well as in India, China, and the Pacific Islands, where prevalence can range from 5 - 80%. A single deletion has little effect on the red blood cell, but two deletions can give rise to alpha thalassemia, a mild microcytic anemia. Patients with sickle cell disease who have two alpha globin deletions tend to have a higher hemoglobin level, smaller red blood cells, and a lower fraction of circulating reticulocytes - consistent with decreased hemolysis and red cell turnover. They also have a lower number of dense or irreversibly sickled cells. These changes might explain why alpha globin deletions reduce the severity of sickle cell disease.

However, a novel function for alpha globin as a regulator of endothelial nitric oxide (NO) has recently been identified that raises new questions about how alpha globin deletions protect against sickle cell disease. We hypothesize that individuals with two alpha globin deletions will have decreased gene expression and protein levels of alpha globin in vascular endothelium, permitting more NO to diffuse across the myoendothelial junction, compared to individuals who have all four alpha globin genes intact. In this protocol we will screen healthy volunteers to identify those with two alpha globin deletions; these individuals as well as matched controls will be referred to a separate protocol to undergo studies of vascular endothelial function.

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Study Type : Observational
Estimated Enrollment : 2000 participants
Observational Model: Other
Time Perspective: Other
Official Title: Screening for Alpha Globin Deletions
Actual Study Start Date : April 17, 2017
Estimated Primary Completion Date : December 31, 2027
Estimated Study Completion Date : December 31, 2027

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Thalassemia

We plan to perform genetic screening of up to 2,000 individuals of African ancestry, an ethnic group with a high prevalence of alpha thalassemia.

Primary Outcome Measures :
  1. Identify Presence of Double Alpha Globin Deletions in Healthy Volunteers. [ Time Frame: Ongoing ]
    As this is not a treatment protocol, there is no primary endpoint. The primary objective is to identify presence of double alpha globin deletions in healthy volunteers.

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

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Ages Eligible for Study:   18 Years to 39 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Sampling Method:   Non-Probability Sample
Study Population
All subjects ages 18 through 39 will be considered for the protocol. We have excluded anyone age 40 and older in order to avoid confounders of older age and cardiovascular disease in asymptomatic subjects. No subject will be excluded from participation based on gender. Subjects will be enrolled based on self-report of African ancestry given the higher prevalence of the genetic mutation in these populations.

Subject report of the following:

  1. Age 18 - 39
  2. Self-report of African ancestry
  3. Willingness and legal ability to give and sign informed study consent


There are no exclusion criteria for this screening protocol

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02692872

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Contact: Mary J Jackson, R.N. (301) 761-5667 alpha.study@nih.gov
Contact: Amy P Ruhl, M.D. (240) 669-5776 parker.ruhl@nih.gov

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United States, Maryland
National Institutes of Health Clinical Center Recruiting
Bethesda, Maryland, United States, 20892
Sponsors and Collaborators
National Institute of Allergy and Infectious Diseases (NIAID)
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Principal Investigator: Amy P Ruhl, M.D. National Institute of Allergy and Infectious Diseases (NIAID)
Additional Information:
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Responsible Party: National Institute of Allergy and Infectious Diseases (NIAID)
ClinicalTrials.gov Identifier: NCT02692872    
Other Study ID Numbers: 160065
First Posted: February 26, 2016    Key Record Dates
Last Update Posted: January 27, 2023
Last Verified: January 25, 2023
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No
Plan Description: .The IPD is not required for non-interventional, non-clinical trials.

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
Keywords provided by National Institutes of Health Clinical Center (CC) ( National Institute of Allergy and Infectious Diseases (NIAID) ):
Alpha Thalassemia
Double Deletion
Additional relevant MeSH terms:
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Anemia, Hemolytic, Congenital
Anemia, Hemolytic
Hematologic Diseases
Genetic Diseases, Inborn