Patient description: The patient is a 16-year-old girl recently diagnosed with myasthenia gravis, class IIa. She complains of diplopia and weakness affecting in her upper extremities. She had a positive anti-AChR antibody test, and her single fiber electromyography (SFEMG) was positive. She is on acetylcholinesterase inhibitor treatment combined with immunosuppressants. But she still has some symptoms. She does not smoke or use illicit drugs. She is not sexually active, and her menses are regular. Her physical exam and lab studies are not remarkable for any other abnormalities. BP: 110/75 Hgb: 11 g/dl WBC: 8000 /mm3 Plt: 300000 /ml Creatinine: 0.5 mg/dl BUN: 10 mg/dl Beta hcg: negative for pregnancy

Clinical trial eligibility criteria: eligible ages (years): 50.0-75.0,  Atypical Chronic Myeloid Leukemia, BCR-ABL1 Negative Chronic Myelomonocytic Leukemia de Novo Myelodysplastic Syndrome Essential Thrombocythemia Myeloproliferative Neoplasm Paroxysmal Nocturnal Hemoglobinuria Polycythemia Vera Polycythemia Vera, Post-Polycythemic Myelofibrosis Phase Primary Myelofibrosis Refractory Anemia Refractory Anemia With Excess Blasts Refractory Anemia With Ring Sideroblasts Refractory Cytopenia With Multilineage Dysplasia Refractory Cytopenia With Multilineage Dysplasia and Ring Sideroblasts Patients aged >= 50 and < 75 years (yrs) with CMML, or previously untreated MDS or MPD Patients aged < 50 yrs at high risk for regimen related toxicity using standard high dose regimens; factors considered high risk pre-existing conditions such as a chronic disease affecting kidneys, liver, lungs, or heart or previous failed HCT An human leukocyte antigen (HLA)-identical related or an HLA-matched unrelated donor (Fred Hutchinson Cancer Research Center [FHCRC] matching allowed will be Grade 1.0 to 2.1) is available Recovery from the effects of previous chemotherapy, with a minimum of 21 days from initiation of last therapy; hydroxyurea or anagrelide may be used to manage elevated cell counts in patients up to the time they begin therapy under this protocol Patients < 12 yrs of age must be discussed on a case by case basis with the primary investigator (PI) of the protocol prior to registration A signed informed consent form or minor assent form MDS: MDS classifiable by the World Health Organization (WHO) system as RA, RARS, refractory cytopenia with multilineage dysplasia (RCMD), RCMD and ringed sideroblasts (RCMD-RS) or RAEB MDS: No previous myelosuppressive therapy; for the purpose of this protocol myelosuppressive chemotherapy will be defined as chemotherapy given with the intent of inducing a complete remission (e.g., standard 7+3, high dose intermittent ARA-C [HIDAC], or Mylotarg) MDS: Patients must have < 10% marrow blasts; fewer than 10% marrow blasts must be documented by marrow examination within 3 weeks of initiation of conditioning CMML: Patients with CMML1 who have not received myelosuppressive therapy must have < 10% marrow blasts; fewer than 10% marrow blasts must be documented by marrow examination within 3 weeks of initiation of conditioning; OR patients with CMML who have progressed beyond CMML1 and have received myelosuppressive chemotherapy must have < 5% marrow blasts; fewer than 5% marrow blasts must be documented by marrow examination within 3 weeks of initiation of conditioning  Organ dysfunction as defined by the following Symptomatic coronary artery disease or cardiac ejection fraction < 35% (or, if unable to obtain ejection fraction, shortening fraction of < 26%); if shortening fraction is < 26% a cardiology consult is required with the principal investigator (PI) having final approval of eligibility; ejection fraction is required if age > 50 years or there is a history of anthracycline exposure or history of cardiac disease Diffusing capacity of the lung for carbon monoxide (DLCO) < 35%, TLC < 35%, forced expiratory volume (FEV)1 < 35% and/or receiving supplementary continuous oxygen; the FHCRC PI of the study must approve of enrollment of all patients with pulmonary nodules Liver function abnormalities: Patient with clinical or laboratory evidence of liver disease will be evaluated for the cause of liver disease, its clinical severity in terms of liver function, bridging fibrosis, and the degree of portal hypertension; the patient will be excluded if he/she is found to have fulminant liver failure, cirrhosis of the liver with evidence of portal hypertension, alcoholic hepatitis, esophageal varices, a history of bleeding esophageal varices, hepatic encephalopathy, uncorrectable hepatic synthetic dysfunction evinced by prolongation of the prothrombin time, ascites related to portal hypertension, bacterial or fungal liver abscess, biliary obstruction, chronic viral hepatitis with total serum bilirubin > 3mg/dL, or symptomatic biliary disease Bone marrow documenting blast count >= 10% or >= 5% in CMML patients who have progressed beyond CMML1 and received myelosuppressive chemotherapy Patients with active non-hematologic malignancies (except non-melanoma skin cancers); this does not apply to patients with non-hematologic malignancies that do not require therapy Patients with a history of non-hematologic malignancies (except non-melanoma skin cancers) currently in a complete remission, who are less than 5 years from the time of complete remission, and have a > 20% risk of disease recurrence Presence of >= 5% circulating leukemic blasts (in the peripheral blood) detected by standard pathology Active central nervous system (CNS) involvement of disease Karnofsky performance score < 70% or Lansky-Play Performance score < 70 for pediatric patients