Successful HLA-identical bone marrow transplantation in a patient with PNP deficiency using busulfan and fludarabine for conditioning.

PNP deficiency is an autosomal recessive metabolic disorder characterized by severe combined immunodeficiency and by complex neurological symptomatology including ataxia, developmental delay and spasticity. Patients usually die in the first or second decade of life due to recurrent infections. The only curative treatment is bone marrow transplantation (BMT). We describe a 22-month-old girl who underwent BMT from her HLA-identical brother. Conditioning consisted of busulfan and fludarabine only, resulting in low toxicity and prompt engraftment. At 18 months after BMT, the girl has developed normal immunological functions, and her neurological status has improved.