Background: Reduced harvest volumes in pediatric donors appear to have the potential to reduce donor-associated risks while maintaining engraftment in recipients; however, the allowable harvest volume reduction remains undefined. Methods: We retrospectively analyzed the data pairs of 553 bone marrow (BM) harvests from pediatric (age at harvest ＜18 yr) sibling donors and clinical outcomes of 553 pediatric (age at infusion ＜14 yr) transplant-naïve recipients to assess the optimal BM harvest volume needed from pediatric donors to obtain the desired CD34+ cell count (≥3.0×10 6 cells per kg of recipient weight), and to study its impact on the clinical outcomes of transplantation in pediatric recipients. Results: The minimum desired CD34+ cell count of ≥3.0×10 6 per kg of recipient weight was achieved for 506 (95.3%) of donor-recipient pairs. The median CD34+ cell yield was 6.4×10 6 per kg of recipient weight (range, 1.2‒33.8×10 6 ) in donors younger than 5 years old at harvest, 4.7×10 6 (range, 0.3‒28.5×10 6 ) in donors aged 5‒10 years and 2.1×10 6 range, 0.3‒11.3×10 6 ) in donors older than 10 years (P ＜0.001). Conclusion The infused CD34+ cell dose (×10 6 cells/kg of recipient weight) had no impact on GRFS; however, a CD34+ cell dose of ＞7×10 6 cells/kg of recipient weight did not improve hematopoietic recovery

Background: Our study was designed to investigate the frequencies and distributions of familial hemophagocytic lymphohistiocytosis (FHL) associated genes in Saudi patients. Methods: FHL associated gene screening was performed on 87 Saudi patients who were diagnosed with hemophagocytic lymphohistiocytosis (HLH) between 1995 and 2014. The clinical and biochemical profiles were also retrospectively captured and analyzed. Results: Homozygous mutations and mono-allelic variants were identified in 66 (75.9%) and 3 (3.5%) of the study participants, respectively. STXBP2 was the most frequently mutated gene (36% of patients) and mutations in STXBP2 and STX11 accounted for 58% of all FHL cases and demonstrated a specific geographical pattern. Patients in the FHL group presented at a significantly younger age than those belonging to the unknown-genetics group (median, 3.9 vs. 9.4 mo; P =0.005). The presenting clinical features were similar among the various genetic groups and the 5-year overall survival (OS) was 55.4% with a 5.6 year median follow-up. Patients with PRF1 mutations had a significantly poorer 5-year OS (21.4%, P =0.008) and patients undergoing hematopoietic stem cell transplant (72.4%) had a significantly better 5-year OS (66.5% vs. 0%, P =0.001). Conclusion Our study revealed the predominance of the STXBP2 mutations in Saudi patients with FHL. A genetic diagnosis was possible in 80% of the cohort and our data showed improved survival in FHL patients who underwent hematopoietic stem cell transplant.

Background: Our study was designed to investigate the frequencies and distributions of familial hemophagocytic lymphohistiocytosis (FHL) associated genes in Saudi patients. Methods: FHL associated gene screening was performed on 87 Saudi patients who were diagnosed with hemophagocytic lymphohistiocytosis (HLH) between 1995 and 2014. The clinical and biochemical profiles were also retrospectively captured and analyzed. Results: Homozygous mutations and mono-allelic variants were identified in 66 (75.9%) and 3 (3.5%) of the study participants, respectively. STXBP2 was the most frequently mutated gene (36% of patients) and mutations in STXBP2 and STX11 accounted for 58% of all FHL cases and demonstrated a specific geographical pattern. Patients in the FHL group presented at a significantly younger age than those belonging to the unknown-genetics group (median, 3.9 vs. 9.4 mo; P =0.005). The presenting clinical features were similar among the various genetic groups and the 5-year overall survival (OS) was 55.4% with a 5.6 year median follow-up. Patients with PRF1 mutations had a significantly poorer 5-year OS (21.4%, P =0.008) and patients undergoing hematopoietic stem cell transplant (72.4%) had a significantly better 5-year OS (66.5% vs. 0%, P =0.001). Conclusion Our study revealed the predominance of the STXBP2 mutations in Saudi patients with FHL. A genetic diagnosis was possible in 80% of the cohort and our data showed improved survival in FHL patients who underwent hematopoietic stem cell transplant.