An observational study in Sickle Cell Trait, Sickle Cell Disease and Sickle Cell Anemia, sponsored by National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Recruiting at 1 site in United States. Open to participants aged 18 Years to 100 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-26.
Sponsored by National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) · Observational
This study will collect representative blood samples from healthy children and adults and from children and adults who have unique red blood cell features that are related to sickle cell disease. Sickle cell disease is a blood disease that limits the ability of red blood cells to carry oxygen throughout the body. The purpose of the study is to collect a variety of blood samples that may then be used to investigate advances and potential new drug treatments for sickle cell disease.
Volunteers must be at least 18 years of old. Samples will be taken both from healthy volunteers and from volunteers who have unique red blood cell features that are related to sickle cell disease. Candidates will be screened with a medical history.
During the study, participants will undergo a one- to two-hour outpatient procedure at the National Institutes of Health Clinical Center. Once researchers have explained the study and obtained the participant s consent, participants will donate 8 cc (approximately 2 teaspoons) of blood.
Because repeat testing helps researchers validate study findings, participants who have the unique red blood cell features mentioned above may also be asked if they are willing to return and donate another 2 cc to 8 cc of blood for additional studies. The amount of blood drawn will not exceed 50 ml with any eight-week period for adults or 7 cc within any six-week period for children.
The critical event leading to serious morbidity in sickle cell disease is polymerization of the abnormal hemoglobin to form fibers that stiffen and distort red blood cells and consequently, cause vaso-occlusion in the small vessels of the tissues. Currently, hydroxyurea is the only approved drug for treating sickle cell disease, but is only partially effective. This protocol seeks to identify by high sensitivity in vitro screening methods additional compounds that inhibit sickling. Subjects with sickle cell trait or disease and normal volunteers will be asked to donate blood samples for studies to verify their hemoglobinopathies and then periodically donate small volume samples of fresh blood for use in ongoing high throughput screening tests to identify potentially clinically useful anti-sickling drugs.
43 studies on the registry are indexed under Sickle Cell Trait; 11 are open to participants now.
This study's planned enrollment of 250 is above the median of 109 across 20 observational studies indexed under Sickle Cell Trait.
Browse Sickle Cell Trait studies →National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) is the lead sponsor of 538 studies on the registry; 55 are open to participants now.
Of its 80 completed or terminated interventional studies of FDA-regulated products, 51 (64%) have results posted.
Counted across the registry records on this site, refreshed daily.
primary clinical
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
EXCLUSION CRITERIA:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Hemoglobin (Hb)
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Healthy Volunteers
Patient with sickle cell trait or disease
To screen large compound libraries for anti-sickling activity, particularly compounds that are already FDA-approved drugs, with the goal of discovering a drug for treating sickle cell disease.
To identify by high sensitivity in vitro screening methods additional compounds that inhibit sickling
Time frame: daily
Started Nov 2007 (actual).
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) →