Haematopoietic cell transplantation for 106 infants and preschoolers with acquired and inherited bone marrow failures.

Aplastic anaemia in infants and young children presents unique challenges due to high prevalence of inherited bone marrow failure syndromes (IBMFS) in this age group. The objective of this study is assessing clinical characteristics and outcomes of haematopoietic cell transplantation in children ≤5 years with bone marrow failure syndromes. We analysied 106 patients (66% males), median age 4.6 years, including 40 with Fanconi anaemia (FA), 32 with Acquired Severe Aplastic anaemia (aSAA), 15 with Diamond-Blackfan Anaemia, 11 with Amegakaryocytic Purpura and 8 with other IBMFS. Molecular testing was limited (39%), with 25.4% confirmed genetically. Retrospective longitudinal study across three paediatric transplantation centres (1982-2020). Overall survival (OS) was 76.4% over a median 10-year follow-up. OS rates were similar between aSAA and IBMFS (FA 77.5%, other IBMFS 76.5%). Transplant-related mortality (TRM) was lower in aSAA (9.4%) compared with IBMFS (16.2%). Recent years showed improved outcomes, with TRM declining post-2010. Choice of stem cell source impacted OS, favouring bone marrow over umbilical cord, but showing encouraging results with haploidentical. Late complications were common, including endocrine-metabolic issues and delayed neuropsychomotor development. Diagnosing and managing bone marrow failures in young children pose significant challenges. Despite advancements in transplant practices, ongoing vigilance and comprehensive care are necessary to improve long-term survival rates.

Long-term Survival, Organ Function, and Malignancy after Hematopoietic Stem Cell Transplantation for Fanconi Anemia.

We report on long-term survival in 157 patients with Fanconi anemia (FA) who survived 2 years or longer after their first transplantation with a median follow-up of 9 years. Marrow failure (80%) was the most common indication for transplantation. There were 20 deaths beyond 2 years after transplantation, with 12 of the deaths occurring beyond 5 years after transplantation. Donor chimerism was available for 149 patients: 112 (76%) reported > 95% chimerism, 27 (18%) reported 90% to 95% chimerism, and 8 (5%) reported 20% to 89% donor chimerism. Two patients have < 20% donor chimerism. The 10- and 15-year probabilities of survival were 90% and 79%, respectively. Results of multivariate analysis showed higher mortality risks for transplantations before 2003 (hazard ratio [HR], 7.87; P = .001), chronic graft-versus-host disease (GVHD) (HR, 3.80; P = .004) and squamous cell carcinoma after transplantation (HR, 38.17; P < .0001). The predominant cause of late mortality was squamous cell carcinoma, with an incidence of 8% and 14% at 10 and 15 years after transplantation, respectively, and was more likely to occur in those with chronic GVHD. Other causes of late mortality included chronic GVHD, infection, graft failure, other cancers, and hemorrhage. Although most patients are disease free and functional long term, our data support aggressive surveillance for long periods to identify those at risk for late mortality.

TLR8-dependent TNF-(alpha) overexpression in Fanconi anemia group C cells.

Tumor necrosis factor alpha (TNF-alpha) production is abnormally high in Fanconi anemia (FA) cells and contributes to the hematopoietic defects seen in FA complementation group C-deficient (Fancc(-/-)) mice. Applying gene expression microarray and proteomic methods to studies on FANCC-deficient cells we found that genes encoding proteins directly involved in ubiquitinylation are overrepresented in the signature of FA bone marrow cells and that ubiquitinylation profiles of FA-C and complemented cells were substantially different. Finding that Toll-like receptor 8 (TLR8) was one of the proteins ubiquitinylated only in mutant cells, we confirmed that TLR8 (or a TLR8-associated protein) is ubiquitinylated in mutant FA-C cells and that TNF-alpha production in mutant cells depended upon TLR8 and the canonical downstream signaling intermediates interleukin 1 receptor-associated kinase (IRAK) and IkappaB kinase-alpha/beta. FANCC-deficient THP-1 cells and macrophages from Fancc(-/-) mice overexpressed TNF-alpha in response to TLR8 agonists but not other TLR agonists. Ectopically expressed FANCC point mutants were capable of fully complementing the mitomycin-C hypersensitivity phenotype of FA-C cells but did not suppress TNF-alpha overproduction. In conclusion, FANCC suppresses TNF-alpha production in mononuclear phagocytes by suppressing TLR8 activity and this particular function of FANCC is independent of its function in protecting the genome from cross-linking agents.

A strategy for molecular diagnostics of Fanconi anemia in Brazilian patients.

BACKGROUND: Fanconi anemia (FA) is a predominantly autosomal recessive disease with wide genetic heterogeneity resulting from mutations in several DNA repair pathway genes. To date, 21 genetic subtypes have been identified. We aimed to identify the FA genetic subtypes in the Brazilian population and to develop a strategy for molecular diagnosis applicable to routine clinical use. METHODS: We screened 255 patients from Hospital de Clínicas, Universidade Federal do Paraná for 11 common FA gene mutations. Further analysis by multiplex ligation-dependent probe amplification (MLPA) for FANCA and Sanger sequencing of all coding exons of FANCA, -C, and -G was performed in cases who harbored a single gene mutation. RESULTS: We identified biallelic mutations in 128/255 patients (50.2%): 89, 11, and 28 carried FANCA,FANCC, and FANCG mutations, respectively. Of these, 71 harbored homozygous mutations, whereas 57 had compound heterozygous mutations. In 4/57 heterozygous patients, both mutations were identified by the initial screening, in 51/57 additional analyses was required for classification, and in 2/57 the second mutation remained unidentified. We found 52 different mutations of which 22 were novel. CONCLUSION: The proposed method allowed genetic subtyping of 126/255 (49.4%) patients at a significantly reduced time and cost, which makes molecular diagnosis of FA Brazilian patients feasible.