Observational Study to Deeply Phenotype Major Organs in Sickle Cell Disease After Curative Therapies

* INCLUSION CRITERIA:

In order to be eligible to participate in this study, an individual must meet all of the following criteria:

1. Stated willingness to comply with all study procedures and availability for the duration of the study
2. Male or female, aged \>=18 years
3. Patients with current or previous diagnosis of any type of SCD (including HbSS, HbSC, HbSbeta\^0-thal, HbSbeta\^+-thal) who:

   1. plan to receive an allogeneic HCT or gene therapy,

      Or
   2. are receiving non-curative treatment (standard of care or investigational) and who do not plan to receive an allogeneic HCT or gene therapy
4. Ability to travel to the NIH Clinical Center
5. Ability of subject to understand a written informed consent document.
6. At least one of the following eligibility criteria:

   * History of stroke (including silent stroke) or abnormal transcranial doppler examination (\>= 200 m/s)
   * Progression of central nervous system vasculopathy on MRA
   * History of SCD-related renal insufficiency defined as nephrotic syndrome OR creatinine clearance \< 60mL/min OR a creatinine level \>=1.3 mg/dL AND kidney biopsy consistent with sickle cell nephropathy
   * Tricuspid regurgitant velocity \>= 2.5 m/s
   * Recurrent tricorporal priapism defined as at least 2 episodes of an erection lasting \> 4 hours involving the corpora cavernosa and corpus spongiosa
   * SCD-associated liver disease defined as EITHER ferritin \> 1000 mcg/L OR direct bilirubin \> 0.4 mg/dL
   * \> 1 hospitalization per year for vaso-occlusive crises while receiving hydroxyurea treatment
   * A history of 2 or more acute chest syndrome episodes in the participant's lifetime.
   * Avascular necrosis of 2 or more joints
   * Red cell alloimmunization (delayed hemolytic transfusion reaction or significant red blood cell alloimmunization that makes transfusion difficult).
   * Administration of regular red blood cell (RBC) transfusion therapy (\>=8 red cell transfusions in the previous 12 months) to prevent SCD complications (i.e. pain, stroke, or acute chest syndrome).
   * Eligible for an allogeneic HCT or gene therapy at an outside transplant center.

EXCLUSION CRITERIA:

All individuals meeting any of the exclusion criteria at baseline will be excluded from study participation.

1. Prior transplantation (including but not limited to HSCT and kidney transplant)
2. Pregnant or breastfeeding
3. Patients with allergy to iodine or iodinated contrast solutions will not undergo Iothalamate or Iohexol GFR clearance testing but can undergo the other deep phenotype testing
4. Implanted metal object that is not compatible with MRI (e.g.: cerebral aneurysm clip, cochlear implant, or pacemaker)
5. Patients with a pacemaker or automated implantable cardioverter defibrillator will not undergo VCTE but can enroll and undergo the other deep phenotype testing as long as the device is compatible with MRI and MRI testing can be performed
6. Patients requiring peritoneal or hemodialysis
7. Uncontrolled infection or acute illness