Avatrombopag for Platelet Recovery Post-UCBT in Patients With Bone Marrow Failure Disease

Inclusion Criteria: * Age ≥12 years old, male or female; * Patients diagnosed with bone marrow failure disease including aplastic anemia (AA), Fanconi anemia (FA), paroxysmal nocturnal hemoglobinuria (PNH) and undergoing UCBT; * ECOG score ≤2; * Voluntary participation in this clinical trial, patients fully understand the trial content and sign the informed consent； Exclusion Criteria: * Pregnant or lactating women； * Known allergy to Avatrombopag; * A history of severe thrombotic events or known risk factors for thrombosis or active thromboembolism requiring anticoagulation; * A history of platelet dysfunction or bleeding prone disease or severe bleeding (requiring more than 2 units of red blood cell infusion or a hematocrit drop of ≥10%) within 7 days prior to screening; * Chronic active hepatitis B and C; * Repeat or multiple transplantation or multiple organ transplantation; * HIV positive, EBV-DNA positive, CMV-DNA positive; * Have severe infection or complicated with serious heart, liver, lung, kidney, neurological or metabolic diseases; * A serious adverse event (Level 4 or 5) as defined by the Standard General Terminology for Adverse Events Version 4.0 occurred during the pre-treatment period; * Participants participate in another clinical study with any exploratory drug or device within 30 days prior to baseline visit; Observational studies are allowed; * Subjects with cognitive impairment or uncontrolled mental illness; * Subjects and/or authorized family members to refuse treatment with Avatrombopag; * Those who are judged by the researchers as not suitable for inclusion (such as accompanying medical history, which may affect the safety of the subjects or it is estimated that the treatment cannot be adhered to due to financial problems).