Protocol Title: Safety and Feasibility of Autologous CD34+ Hematopoietic Stem Cells Mobilization and Apheresis in Participants With RUNX1 Familial Platelet Disorder

Exclusion Criteria

• •Participants who meet any of the following criteria are excluded from the study:
• •1. Participants with cognitive impairments and/or any serious unstable pre-existing medical condition or psychiatric disorder that can interfere with safety or with obtaining informed consent or compliance with study procedures.
• •2. Have uncontrolled bleeding
• •3. Are using supplemental oxygen
• •4. Have known severe splenomegaly (≥ 20 cm)
• •5. Have a diagnosis of MDS or hematologic malignancies, as defined by WHO hematolymphoid tumor classification fifth edition (Khourey et al 2022) hematolymphoid tumor classification fifth edition (Khourey et al 2022)
• •6. Have recent prior malignancies except resected basal cell carcinoma or treated cervical carcinoma in situ Note: Cancer treated with curative intent \< 5 years previously may be allowed following approval from the study investigator. Cancer treated with curative intent \> 5 years previously is allowed.
• •7. Have any prior or current myeloproliferative or a significant coagulation or immunodeficiency disorder
• •8. Have advanced liver disease, defined as any of the following:
• •1. Persistent aspartate transaminase, alanine transaminase, or direct bilirubin value \> 5× the upper limit of normal (ULN) at screening
• •2. Screening prothrombin time (PT) or partial thromboplastin time (PTT) \> 1.5× ULN
• •9. Have had prior HSCT or gene therapy
• •10. Have history of concomitant sickle cell disease
• •11. Have been treated with an investigational drug within 30 days of screening or 5 half-lives (whichever is longer)
• •12. Have a positive test result for HIV, hepatitis B virus (HBV), or hepatitis C virus (HCV) at screening
• •1. Participants with positive hepatitis B core antibody (HbcAb) and/or hepatitis B-e antibody (HbeAb) are eligible provided viral load is negative by quantitative polymerase chain reaction (qPCR).
• •2. Participants who are positive for anti-hepatitis C antibody are eligible as long as they have a negative HCV viral load by qPCR.
• •13. Have a positive infectious disease panel at screening for human T-lymphotropic virus 1 or 2 (HTLV-1 and HTLV-2), or syphilis (rapid plasma 24 reagin \[RPR\])
• •14. Have clinically significant and active bacterial, viral, fungal, or parasitic infection at screening
• •15. Have a white blood cell (WBC) count \< 2 × 109/L
• •16. Have a left ventricular ejection fraction \< 45%
• •17. Have a screening estimated glomerular filtration rate \< 60 mL/min/1.73 m2
• •18. Have a diagnosis of a significant psychiatric disorder that could seriously impede the ability to participate in the study
• •19. For women of childbearing potential: are pregnant or breastfeeding or lack adequate contraception
• •20. Are unable to comply with the study procedures, as assessed by the investigator