Sinusoidal Obstruction Syndrome for Stem Cell Transplant Patients Biomarker Study

Inclusion Criteria: Age ≤ 25 years undergoing HCT for any reason who fulfill any ONE (1) of the following criteria: 1. History of hepatic disease as defined by: 1. Viral hepatitis (i.e., hepatitis C virus \[HCV\]) 2. Liver tumor before HCT 3. Hepatic fibrosis or cirrhosis before HCT as proven by liver biopsy 4. High aspartate aminotransferase (AST) (\> 2x ULN) before HCT (pre-transplant evaluation) 5. High alanine transaminase (ALT) (\> 2x ULN) before HCT 6. High bilirubin (\> 1.2x ULN) before HCT 2. HCT high-risk features including: a. Conditioning with high-risk modalities including: i. Busulfan (BU)-containing regimen particularly with oral BU + cyclophosphamide ii. TBI-containing regimen, particularly cyclophosphamide + total-body irradiation (TBI) b. ≥ 2 HCT c. Allo-HCT for leukemia \> or = second relapse d. Unrelated donor (URD) HCT e. Human leukocyte antigen (HLA) mismatch HCT (less than 10 of 10 for bone marrow/peripheral blood stem cell \[BM/PBSC\] or anything less than 6 of 6 for UCB) f. Use of sirolimus + tacrolimus prophylaxis for GVHD 3. High-risk disease states including: 1. Juvenile myelo-monocytic chronic leukemia (JMML) 2. Primary hemophagocytic lymphohistiocytosis (HLH) 3. Adrenoleukodystrophy 4. Osteopetrosis 4. Other high-risk features including: 1. Prior treatment with gemtuzumab ozogamicin 2. Use of hepatotoxic drugs 1 month before HCT and during HCT 3. Iron overload (i.e., thalassemia/sickle cell) with serum ferritin \> 1000ng/ml 4. Deficit of ATIII, T-PA (i.e., \< 30% normal values), and resistance to activated protein C if clinical indication (these values do not have to be specifically checked if no clinical history) 5. Young age \< 2 years but more than 1 month Exclusion Criteria: Patients who are transplanted but do not fulfill any of the above mentioned criteria.