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

PNP deficiency is an autosomal recessive metabolic disorder characterized b y severe combined immunodeficiency and by complex neurological symptomatolo gy including ataxia, developmental delay and spasticity. Patients usually d ie in the first or second decade of life due to recurrent infections. The o nly curative treatment is bone marrow transplantation (BMT). We describe a 22-month-old girl who underwent BMT from her HLA-identical brother. Conditi oning consisted of busulfan and fludarabine only, resulting in low toxicity and prompt engraftment. At 18 months after BMT, the girl has developed nor mal immunological functions, and her neurological status has improved.