Pilot Study of Reduced-Intensity Hematopoietic Stem Cell Transplant of DOCK8 Deficiency

* INCLUSION CRITERIA - RECIPIENT: * Age of 4-35 years * Weight \>= 12 kilograms * DOCK8 deficiency with the two criteria listed below: * Clinical history of one or more episodes of life-threatening or severely disfiguring infection with opportunistic organisms, including severe recurrent cutaneous and sinopulmonary infections with bacterial or fungal infection, or viral infections with herpes simplex, herpes zoster, Molluscum contagiosum, or human papilloma virus. * Homozygous or compound heterozygous mutations in the DOCK8 gene performed by a CLIA-certified laboratory * Available 10/10 or 9/10 HLA-matched related or unrelated donor or a haploidentical related donor * Left ventricular ejection fraction \> 40%, preferably by 2-D echo. If the subject has radiological evidence of aortic, renal artery, or coronary artery vasculitis, a left ventricular ejection fraction \>30% is acceptable. * Pulmonary Function Tests: FEV1 \> 50% of expected Note: For children who are unable to cooperate for PFTs, the criterion is: No evidence of dyspnea at rest, no exercise intolerance, and no requirement for supplemental oxygen therapy * Creatinine: Subjects: less than or equal to 2.0 mg/dl or creatinine clearance greater than or equal to 30 ml/min/1.73 m\^2. Pediatric subjects (\<18 years old): Creatinine less than or equal to 1.5 mg/dl or a creatinine clearance of greater than or equal to 30 mL/min/1.73 m\^2. * Serum total bilirubin \< 2.5 mg/dl; serum ALT and AST less than or equal to 5 times upper limit of normal. * Subjects, parents/guardian(s), legally authorized representatives (LAR), or durable power of attorney must be able to give consent and sign the informed consent document * Disease status: Subjects with malignancy are to be referred in remission for evaluation, except in the case of viral associated malignancies. Should a subject have progressive disease or a donor becomes unavailable after enrollment, the subject will be referred back to their primary hematologist-oncologist for treatment. If this course of action is not in the best interest of the subject according to the clinical judgment of the PI/LAI, then the subject may receive standard treatment for the malignant disease under the current study. If under either of these settings, it becomes apparent that the subject will not be able to proceed to transplant, then he/she must come off study. Recipient-Subjects receiving a standard therapy will be told about the therapy, associated risks, benefits alternatives of the proposed therapy, and availability of receiving the same treatment elsewhere, outside of a research protocol. EXCLUSION CRITERIA - RECIPIENT: * HIV infection. * Chronic active hepatitis B. Subject may be hepatitis B core antibody positive. For subjects with a concomitant positive hepatitis B surface antigen, the risk-benefit profile of transplant and hepatitis B will be discussed with the subject, and eligibility determined by the PI and the protocol chairperson * History of psychiatric disorder which may compromise compliance with transplant protocol, or which does not allow for appropriate informed consent. * Active CNS involvement by malignancy (subjects with known positive CSF cytology or parenchymal lesions visible by CT or MRI). Except in the case of viral associated malignancies in which case the subject may benefit from the transplant to control the malignancy. * Pregnant or lactating. The effects on human milk are also unknown and may be harmful to the infant; therefore, individuals who are nursing or plan to nurse a child must agree to discontinue/postpone nursing during the interval from study entry to one year post-transplant. * Sexually active individuals capable of becoming pregnant who are unable or unwilling to use effective form(s) of contraception during time enrolled on study and for 1 year post-transplant. Effective forms of contraception include one or more of the following: intrauterine device (IUD), hormonal (birth control pills, injections, or implants), tubal ligation/hysterectomy, partner s vasectomy, barrier methods, (condom, diaphragm, or cervical cap), or abstinence. Individuals who can father children on the protocol must use an effective form of contraception at study entry, and for one year post-transplant. The effects of transplant, the radiation, and the medications used after transplant may be harmful to a fetus. * Presence of active malignancy in another organ system other than the hematopoietic system, except when driven by viruses in which case the immune reconstitution after transplant may control the malignancy. * No available 10/10 or 9/10 HLA-matched related or unrelated donor or haploidentical related donor. DONOR EVALUATION AND SELECTION CRITERIA: All donors will undergo suitability and eligibility determination according with current regulations of the field of hematopoietic cell transplantation. Related donor-recipient pairs will initially undergo low-resolution typing (antigen-level) to aid in the selection of a potential family donor and targeted sequencing of the DOCK8 gene. Heterozygous carriers of a DOCK8 mutation are suitable to donate. Upon review of the familial HLA inheritance pattern, confirmatory and high-resolution (allele-level) typing will be performed on potential fully matched and haploidentical related donors, respectively. Final selection of a related donor will be in consultation with qualified HLA personnel. Secondary donor characteristics as potential predictors of survival have been studied in large populations of donor/recipient pairs from US and European registries. Younger donor age and CMV seropositivity have been associated with improved survival. For the purposes of this study, overall donor health, younger age (\<35 years), CMV seropositivity and ABO matching will also impact selection when multiple donors related or unrelated of equal HLA matching degree are available. INCLUSION CRITERIA FOR FAMILY INTERVIEWS (COMPLETE): * Parent/caregiver of a subject(s) who received a transplant for DOCK8 deficiency on this study. * Transplant recipient \>= 18 who has undergone a transplant for DOCK8 deficiency on this study. Note: If a transplant recipient has completed follow-up or has come off study for any reason, re-enrollment will be permitted to complete the interview. * Must be able to give consent and sign the informed consent document. * Able to understand the English language INCLUSION CRITERIA FOR PATIENT AND CAREGIVER PSYCHOSOCIAL AND QOL ASSESSMENTS DURING HCST: * Caregiver participants are eligible for their own participation if their child (the patient) is between 4-25 years old and undergoing transplantation for DOCK8 deficiency on this study. * Patient participants are eligible for their own participation if 8 years old or older and undergoing transplantation for DOCK8 deficiency on this study. * Patient and caregiver participants must be cognitively able to complete the surveys and interviews. * Patient and caregiver participants must speak and/or read English or Spanish. * Patient and caregiver participants must be able to sign the informed consent or assent document, as applicable.