Long-term follow-up of a patient transplanted for Hunter's disease type IIB: a case report and literature review.

Unlike most other storage diseases and despite clinical experience, the indications for bone marrow transplantation in Hunter's disease remain controversial. The case of a 14-year-old male with mucopolysaccharidosis type IIB is presented, who received an allograft from his HLA-identical sibling. The donor had been off therapy for acute lymphoblastic leukemia for 3 years. The patient experienced minimal difficulties with his transplant and was fully engrafted by day 42, with no signs of acute or chronic graft-versus-host disease. Now, more than 3 years after BMT, the patient has experienced significant subjective and objective improvement in his disease. The iduronate-2-sulfatase levels in the serum are now approximately 10% of normal control. Urinary glycosaminoglycans were negative. The posttransplant marrow was evaluated for donor-recipient source using VNTR analysis with the polymerase chain reaction (PCR). This showed a PCR-detectable subpopulation of residual patient marrow cells remaining, suggesting a state of stable mixed chimerism. The patient continues to show signs of amelioration of his disease. These results may be of value in determining the proper therapy for a patient with mild Hunter's disease, and may also be pertinent to the future application of recombinant enzyme therapy or gene therapy.