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Mobilization of suitable amounts of PBSCs with granulocyte-CSF (G-CSF) can be difficult in children. We report the results of using plerixafor in pediatric patients who failed to mobilize progenitors with G-CSF-based regimens. Thirty-three patients, median age 9 years (range 1-18 years) and median weight 29 kg (range 10-85 kg) were enrolled into the study. After 4 days of G-CSF stimulation, the median CD34+ cell count in peripheral blood was 10.4 per μL (range 0.27-23.0 per μL). Plerixafor was administered subcutaneously (0.24 μg/kg in 30 patients and 0.3 μg/kg in 3 patients) 11-12 h before apheresis. At the time of apheresis, CD34+ cell counts increased to a median of 44.1 per μL (range 8.4-357.0 per μL), a median 4.4-fold increase. Two patients (6%) failed to mobilize. Thirty-one patients underwent apheresis and in 27 >2 × 10(6) CD34+ cells per kg of body weight were collected after one procedure. In total, 31 of 33 patients mobilized successfully and the median number of cryopreserved CD34+ cells was 5.6 × 10(6) /kg body weight (2.7 × 10(6)-27.4 × 10(6)). Twenty-four patients underwent transplantation. Engraftment was achieved in all but one patient, who died on day +9 after hematopoietic stem cell transplantation. The median time of neutrophil and platelet recovery was day +12 and +16, respectively. Our study confirms that plerixafor has impressive efficacy and very modest toxicity in children.

Two groups of hereditary diseases are considered. One group is characterized by chromosomal instability (Fanconi's anemia, ataxiatelenagioectasia, xeroderma pigmentosum). The other group includes diseases with marked genotypic changes (Down's disease, cystic fibrosis). All these diseases predispose to malignant neoplasms and premature ageing, which is due to different manifestations of oxidative stress. The paper gives in greatest detail the mechanism responsible for Fanconi's anemia which has been much studied by the authors. Chromosomal instability in this disease is associated with regeneration defect in DNA impaired by oxygen radicals.