Revisiting the first reported case of aplastic anaemia.

The great pathologist Paul Ehrlich in Berlin is commonly credited with describing the first clear case of aplastic anaemia in 1888: a 21-year-old woman who presented with haemorrhage and signs and symptoms of severe anaemia, quickly succumbing to her illness. Ehrlich's description of this patient's background and clinical course allowed individual identification. Re-analysis of this case suggests an inherited bone marrow failure syndrome as a possible additional diagnosis.

Ataluren improves myelopoiesis and neutrophil chemotaxis by restoring ribosome biogenesis and reducing p53 levels in Shwachman-Diamond syndrome cells.

Shwachman-Diamond syndrome (SDS) is characterized by neutropenia, exocrine pancreatic insufficiency and skeletal abnormalities. SDS bone marrow haematopoietic progenitors show increased apoptosis and impairment in granulocytic differentiation. Loss of Shwachman-Bodian-Diamond syndrome (SBDS) expression results in reduced eukaryotic 80S ribosome maturation. Biallelic mutations in the SBDS gene are found in ~90% of SDS patients, ~55% of whom carry the c.183-184TA>CT nonsense mutation. Several translational readthrough-inducing drugs aimed at suppressing nonsense mutations have been developed. One of these, ataluren, has received approval in Europe for the treatment of Duchenne muscular dystrophy. We previously showed that ataluren can restore full-length SBDS protein synthesis in SDS-derived bone marrow cells. Here, we extend our preclinical study to assess the functional restoration of SBDS capabilities in vitro and ex vivo. Ataluren improved 80S ribosome assembly and total protein synthesis in SDS-derived cells, restored myelopoiesis in myeloid progenitors, improved neutrophil chemotaxis in vitro and reduced neutrophil dysplastic markers ex vivo. Ataluren also restored full-length SBDS synthesis in primary osteoblasts, suggesting that its beneficial role may go beyond the myeloid compartment. Altogether, our results strengthened the rationale for a Phase I/II clinical trial of ataluren in SDS patients who harbour the nonsense mutation.

Diamond-Blackfan anemia, the archetype of ribosomopathy: How distinct is it from the other constitutional ribosomopathies?

Diamond-Blackfan anemia (DBA) was the first ribosomopathy described in humans. DBA is a congenital hypoplastic anemia, characterized by macrocytic aregenerative anemia, manifesting by differentiation blockage between the BFU-e/CFU-e developmental erythroid progenitor stages. In 50 % of the DBA cases, various malformations are noted. Strikingly, for a hematological disease with a relative erythroid tropism, DBA is due to ribosomal haploinsufficiency in 24 different ribosomal protein (RP) genes. A few other genes have been described in DBA-like disorders, but they do not fit into the classical DBA phenotype (Sankaran et al., 2012; van Dooijeweert et al., 2022; Toki et al., 2018; Kim et al., 2017 [1-4]). Haploinsufficiency in a RP gene leads to defective ribosomal RNA (rRNA) maturation, which is a hallmark of DBA. However, the mechanistic understandings of the erythroid tropism defect in DBA are still to be fully defined. Erythroid defect in DBA has been recently been linked in a non-exclusive manner to a number of mechanisms that include: 1) a defect in translation, in particular for the GATA1 erythroid gene; 2) a deficit of HSP70, the GATA1 chaperone, and 3) free heme toxicity. In addition, p53 activation in response to ribosomal stress is involved in DBA pathophysiology. The DBA phenotype may thus result from the combined contributions of various actors, which may explain the heterogenous phenotypes observed in DBA patients, even within the same family.

Human leucocyte antigen-matched related haematopoietic stem cell transplantation using low-dose cyclophosphamide, fludarabine and thymoglobulin in children with severe aplastic anaemia.

When human leucocyte antigen-matched related donors are available, haematopoietic stem cell transplantation (HSCT) in children with severe aplastic anaemia (SAA) represents the standard of care. Cyclophosphamide (Cy) 200 mg/kg and anti-thymocyte globulin (ATG) are frequently administered, but to-date, no standard conditioning regimen exists. In this study, we investigated the efficacy of a unified HSCT conditioning protocol consisting of low-dose Cy 80 mg/kg, fludarabine and ATG. Data were reviewed from children aged ≤14 years with either acquired SAA or non-Fanconi anaemia inherited bone marrow failure syndrome (IBMFS) between 2011 and 2022 at various Saudi institutions. Graft-versus-host disease (GVHD) prophylaxis included mycophenolate mofetil and calcineurin inhibitors. HSCT was performed in 32 children (17 females and 15 males). Nine patients had deleterious mutations (two ERCC6L2, two ANKRD26, two TINF2, one LZTFL1, one RTEL1 and one DNAJC21). Four patients had short telomeres. All 32 patients engrafted successfully. At 3 years post-transplant, the event-free survival was 93% and overall survival was 95%. Two patients experienced secondary graft failure or myelodysplastic syndrome. A low probability of GVHD was observed (one acute GVHD II and one mild chronic GVHD). These data highlight how HSCT using low-dose Cy as part of a fludarabine-based regimen is safe and effective in SAA/non-Fanconi anaemia IBMFS.

How to optimize outcome of patients undergoing HLA-matched related haematopoietic stem cell transplantation in acquired and inherited bone marrow failure syndromes.

Up-front allogeneic haematopoietic stem cell transplantation (allo-HSCT) after a reduced intensity conditioning regimen is the standard treatment in children with acquired severe aplastic anaemia (aSAA) and inherited bone marrow failure syndromes (iBMFs) in the presence of a healthy matched related donor (MRD). The paper by Alsultan et al. report the safety and efficacy of MRD HSCT conditioned with low-dose cyclophosphamide, fludarabine and thymoglobulin in both aSAA and non-Fanconi iBMFs, strengthening the concept of the pivotal role of immunosuppressive approach in allo-HSCT for specific subgroups of non-malignant diseases requiring a reduced risk of toxicities, offering the opportunity to discuss the essential points for achieving patients' long-term survival after MRD HSCT in BMF. Commentary on: Alsultan et al. Human leucocyte antigen-matched related haematopoietic stem cell transplantation using low-dose cyclophosphamide, fludarabine and thymoglobulin in children with severe aplastic anaemia. Br J Haematol 2023;203:255-263.

Poor outcome after hematopoietic stem cell transplantation of patients with unclassified inherited bone marrow failure syndromes.

Classification of inherited bone marrow failure syndromes (IBMFSs) according to clinical and genetic diagnoses enables proper adjustment of treatment. Unfortunately, 30% of patients enrolled in the Canadian Inherited Marrow Failure Registry (CIMFR) with features suggesting hereditability could not be classified with a specific syndromic diagnosis. We analyzed the outcome of hematopoietic stem cell transplantation (HSCT) in unclassified IBMFSs (uIBMFSs) and the factors associated with outcome. Twenty-two patients with uIBMFSs and 70 patients with classified IBMFSs underwent HSCT. Five-year overall survival of uIBMFS patients after HSCT was inferior to that of patients with classified IBMFSs (56% vs 76.5%). The outcome of patients with uIBMFS who received cord blood was significantly lower than that of patients who received other stem cell sources (14.8% vs 90.9%). Engraftment failure was higher among patients with uIBMFS who received cord blood than those who received bone marrow. None of the following factors were significantly associated with poor survival: transfusion load, transplant indication, the intensity of conditioning regimen, human leukocyte antigen-identical sibling/alternative donor. We suggest that identifying the genetic diagnosis is essential to modulate the transplant procedure including conditioning agents and stem cell sources for better outcome and the standard cord blood transplantation (CBT) should be avoided in uIBMFS.

Next-generation sequencing in hypoplastic bone marrow failure: What difference does it make?

Hypoplastic bone marrow failure is a diagnostic feature of multiple haematological disorders, which also share a substantial overlap of clinical symptoms. Hence, discrimination of underlying disorders in patients presenting with hypoplastic bone marrow failure remains a major challenge in the clinic. Recent next-generation sequencing (NGS) studies have broadened our understanding of the varying molecular mechanisms and advanced diagnostics of disorders exhibiting hypoplastic bone marrow failure. In this article, we present a literature review of NGS studies of haematological disorders associated with hypoplastic bone marrow failure and highlight the relevance of NGS for improved clinical diagnostics and decision-making.

Diagnosis and treatment of pediatric myelodysplastic syndromes: A survey of the North American Pediatric Aplastic Anemia Consortium.

BACKGROUND: Myelodysplastic syndromes (MDS) represent a group of clonal hematopoietic stem cell disorders that commonly progress to acute myeloid leukemia (AML). The diagnostics, prognostics, and treatment of adult MDS are established but do not directly translate to children and adolescents. Pediatric MDS is a rare disease, characterized by unique cytogenetics and histology compared with adult MDS, and often arises secondary to germline predisposition or cytotoxic exposures. Our objective was to highlight aspects of diagnosis/management that would benefit from further systematic review toward the development of clinical practice guidelines for pediatric MDS. PROCEDURE: The North American Pediatric Aplastic Anemia Consortium (NAPAAC) is composed of collaborative institutions with a strong interest in pediatric bone marrow failure syndromes and hematologic malignancies. The NAPAAC MDS working group developed a national survey distributed to 35 NAPAAC institutions to assess data on (1) clinical presentation of pediatric MDS, (2) diagnostic evaluation, (3) criteria for diagnosis, (4) supportive care and treatment decisions, and (5) role of hematopoietic stem cell transplantation (HSCT). RESULTS: Twenty-eight of 35 institutions returned the survey. Most centers agreed on a common diagnostic workup, though there was considerable variation regarding the criteria for diagnosis. Although there was consensus on supportive care, treatment strategies, including the role of cytoreduction and HSCT, varied across centers surveyed. CONCLUSIONS: There is lack of national consensus on diagnosis and treatment of pediatric MDS. This survey identified key aspects of MDS management that will warrant systematic review toward the goal of developing national clinical practice guidelines for pediatric MDS.

Nonsense Suppression Therapy: New Hypothesis for the Treatment of Inherited Bone Marrow Failure Syndromes.

Inherited bone marrow failure syndromes (IBMFS) are a group of cancer-prone genetic diseases characterized by hypocellular bone marrow with impairment in one or more hematopoietic lineages. The pathogenesis of IBMFS involves mutations in several genes which encode for proteins involved in DNA repair, telomere biology and ribosome biogenesis. The classical IBMFS include Shwachman-Diamond syndrome (SDS), Diamond-Blackfan anemia (DBA), Fanconi anemia (FA), dyskeratosis congenita (DC), and severe congenital neutropenia (SCN). IBMFS are associated with high risk of myelodysplastic syndrome (MDS), acute myeloid leukemia (AML), and solid tumors. Unfortunately, no specific pharmacological therapies have been highly effective for IBMFS. Hematopoietic stem cell transplantation provides a cure for aplastic or myeloid neoplastic complications. However, it does not affect the risk of solid tumors. Since approximately 28% of FA, 24% of SCN, 21% of DBA, 20% of SDS, and 17% of DC patients harbor nonsense mutations in the respective IBMFS-related genes, we discuss the use of the nonsense suppression therapy in these diseases. We recently described the beneficial effect of ataluren, a nonsense suppressor drug, in SDS bone marrow hematopoietic cells ex vivo. A similar approach could be therefore designed for treating other IBMFS. In this review we explain in detail the new generation of nonsense suppressor molecules and their mechanistic roles. Furthermore, we will discuss strengths and limitations of these molecules which are emerging from preclinical and clinical studies. Finally we discuss the state-of-the-art of preclinical and clinical therapeutic studies carried out for IBMFS.

Outcomes of Hematopoietic Cell Transplantation in Patients with Germline SAMD9/SAMD9L Mutations.

Germline mutations in SAMD9 and SAMD9L genes cause MIRAGE (myelodysplasia, infection, restriction of growth, adrenal hypoplasia, genital phenotypes, and enteropathy) (OMIM: *610456) and ataxia-pancytopenia (OMIM: *611170) syndromes, respectively, and are associated with chromosome 7 deletions, myelodysplastic syndrome (MDS), and bone marrow failure. In this retrospective series, we report outcomes of allogeneic hematopoietic cell transplantation (HCT) in patients with hematologic disorders associated with SAMD9/SAMD9L mutations. Twelve patients underwent allogeneic HCT for MDS (n = 10), congenital amegakaryocytic thrombocytopenia (n = 1), and dyskeratosis congenita (n = 1). Exome sequencing revealed heterozygous mutations in SAMD9 (n = 6) or SAMD9L (n = 6) genes. Four SAMD9 patients had features of MIRAGE syndrome. Median age at HCT was 2.8 years (range, 1.2 to 12.8 years). Conditioning was myeloablative in 9 cases and reduced intensity in 3 cases. Syndrome-related comorbidities (diarrhea, infections, adrenal insufficiency, malnutrition, and electrolyte imbalance) were present in MIRAGE syndrome cases. One patient with a familial SAMD9L mutation, MDS, and morbid obesity failed to engraft and died of refractory acute myeloid leukemia. The other 11 patients achieved neutrophil engraftment. Acute post-transplant course was complicated by syndrome-related comorbidities in MIRAGE cases. A patient with SAMD9L-associated MDS died of diffuse alveolar hemorrhage. The other 10 patients had resolution of hematologic disorder and sustained peripheral blood donor chimerism. Ten of 12 patients were alive with a median follow-up of 3.1 years (range, 0.1 to 14.7 years). More data are needed to refine transplant approaches in SAMD9/SAMD9L patients with significant comorbidities and to develop guidelines for their long-term follow-up.

Molecular analysis and genotype-phenotype correlation of Diamond-Blackfan anemia.

Diamond-Blackfan anemia (DBA) features hypoplastic anemia and congenital malformations, largely caused by mutations in various ribosomal proteins. The aim of this study was to characterize the spectrum of genetic lesions causing DBA and identify genotypes that correlate with phenotypes of clinical significance. Seventy-four patients with DBA from across Canada were included. Nucleotide-level mutations or large deletions were identified in 10 ribosomal genes in 45 cases. The RPS19 mutation group was associated with higher requirement for chronic treatment for anemia than other DBA groups. Patients with RPS19 mutations, however, were more likely to maintain long-term corticosteroid response without requirement for further chronic transfusions. Conversely, patients with RPL11 mutations were less likely to need chronic treatment. Birth defects, including cardiac, skeletal, hand, cleft lip or palate and genitourinary malformations, also varied among the various genetic groups. Patients with RPS19 mutations had the fewest number of defects, while patients with RPL5 had the greatest number of birth defects. This is the first study to show differences between DBA genetic groups with regards to treatment. Previously unreported differences in the rate and types of birth defects were also identified. These data allow better patient counseling, a more personalized monitoring plan, and may also suggest differential functions of DBA genes on ribosome and extra-ribosomal functions.

Pregnancy outcomes in mothers of offspring with inherited bone marrow failure syndromes.

BACKGROUND: Children with inherited bone marrow failure syndromes (IBMFSs) may be symptomatic in utero, resulting in maternal and fetal problems during the pregnancy. Subsequent pregnancies by their mothers should be considered "high risk". METHODS: We retrospectively analyzed outcomes of 575 pregnancies in 165 unaffected mothers of offspring with Fanconi anemia (FA), dyskeratosis congenita (DC), Diamond-Blackfan anemia (DBA), and Shwachman-Diamond syndrome (SDS) for events noted during pregnancy, labor, and delivery. We compared outcomes of pregnancies with affected and unaffected offspring within each group of mothers and with the general population. RESULTS: The rates of miscarriage (12-20%), elective abortion (5-10%), and live birth (68-78%) among mothers of all IBMFS groups were similar and comparable with general population rates but recurrent miscarriages (≥2) were significantly more common in mothers of offspring with DBA and SDS. Offspring with FA were more frequently born small for gestational age (SGA) than unaffected babies (39% vs. 4%) and had fetal malformations (46%) with 18% having three or more, often necessitating early delivery and surgery; offspring with DC had higher rates of SGA (39% vs. 8%) and fetal distress (26% vs. 3%); and offspring with DBA had fetal hypoxia (19% vs. 1%) leading to preterm and emergency cesarean deliveries (26% vs. 6%). Offspring with early-onset severe phenotypes had the most prenatal and peripartum adverse events. CONCLUSION: We identified the high-risk nature of pregnancies in mothers with IBMFS-affected fetuses, suggesting the need for prepregnancy counseling and monitoring of subsequent pregnancies by high-risk fetal-maternal specialists.

Haploidentical Bone Marrow Transplantation with Post-Transplant Cyclophosphamide for Children and Adolescents with Fanconi Anemia.

We describe haploidentical bone marrow transplantation with post-transplant cyclophosphamide (PT-CY) for 30 patients with Fanconi anemia (FA). Twenty-six patients were transplanted upfront, and the preparatory regimens included fludarabine 150 mg/m2 + total body irradiation 200 to 300 cGy ± CY 10 mg/kg without (n = 12) or with rabbit antithymocyte globulin (r-ATG) 4 to 5 mg/kg (n = 14). Four patients were rescued after primary or secondary graft failure after related or unrelated donor transplantation with the above regimen with (n = 2) or without r-ATG (n = 2). PT-CY at 25 mg/kg/day (total dose, 50 mg/kg) followed by cyclosporine and mycophenolate mofetil was given to all patients. All patients engrafted in the subgroup of patients who did not receive r-ATG (n = 14), but their transplant course was complicated by high rates of acute and chronic graft-versus-host disease (GVHD), and only 8 patients are alive. In the subgroup that received r-ATG (n = 16), 14 patients had sustained engraftment, severe GVHD rates were lower, and 13 patients are alive. Hemorrhagic cystitis occurred in 50% of patients, whereas cytomegalovirus reactivation occurred in 75%. One-year overall survival for the entire cohort was 73% (95% CI, 64% to 81%), and all surviving patients achieved full donor chimerism. In conclusion, haploidentical donor transplantation with PT-CY is a suitable option for FA patients without a matched related or unrelated donor.

Late Effects Screening Guidelines after Hematopoietic Cell Transplantation for Inherited Bone Marrow Failure Syndromes: Consensus Statement From the Second Pediatric Blood and Marrow Transplant Consortium International Conference on Late Effects After Pediatric HCT.

Patients with inherited bone marrow failure syndromes (IBMFS), such as Fanconi anemia (FA), dyskeratosis congenita (DC), or Diamond Blackfan anemia (DBA), can have hematologic manifestations cured through hematopoietic cell transplantation (HCT). Subsequent late effects seen in these patients arise from a combination of the underlying disease, the pre-HCT therapy, and the HCT process. During the international consensus conference sponsored by the Pediatric Blood and Marrow Transplant Consortium on late effects screening and recommendations following allogeneic hematopoietic cell transplantation for immune deficiency and nonmalignant hematologic diseases held in Minneapolis, Minnesota in May 2016, a half-day session was focused specifically on the unmet needs for these patients with IBMFS. This multidisciplinary group of experts in rare diseases and transplantation late effects has already published on the state of the science in this area, along with discussion of an agenda for future research. This companion article outlines consensus disease-specific long-term follow-up screening guidelines for patients with IMBFS.

Current Knowledge and Priorities for Future Research in Late Effects after Hematopoietic Cell Transplantation for Inherited Bone Marrow Failure Syndromes: Consensus Statement from the Second Pediatric Blood and Marrow Transplant Consortium International Conference on Late Effects after Pediatric Hematopoietic Cell Transplantation.

Fanconi anemia (FA), dyskeratosis congenita (DC), and Diamond Blackfan anemia (DBA) are 3 of the most common inherited bone marrow failure syndromes (IBMFS), in which the hematologic manifestations can be cured with hematopoietic cell transplantation (HCT). Later in life, these patients face a variety of medical conditions, which may be a manifestation of underlying disease or due to pre-HCT therapy, the HCT, or a combination of all these elements. Very limited long-term follow-up data exist in these populations, with FA the only IBMFS that has specific published data. During the international consensus conference sponsored by the Pediatric Blood and Marrow Transplant Consortium entitled "Late Effects Screening and Recommendations following Allogeneic Hematopoietic Cell Transplant (HCT) for Immune Deficiency and Nonmalignant Hematologic Disease" held in Minneapolis, Minnesota in May of 2016, a half-day session was focused specifically on the unmet needs for these patients with IBMFS. A multidisciplinary group of experts discussed what is currently known, outlined an agenda for future research, and laid out long-term follow-up guidelines based on a combination of evidence in the literature as well as expert opinion. This article addresses the state of science in that area as well as consensus regarding the agenda for future research, with specific screening guidelines to follow in the next article from this group.

Whole exome sequencing in the differential diagnosis of Diamond-Blackfan anemia: Clinical and molecular study of three patients with novel RPL5 and mosaic RPS19 mutations.

Diamond-Blackfan anemia (DBA) is a rare congenital disorder presenting remarkable phenotypic overlap with other inherited bone marrow failure syndromes, making differential diagnosis challenging and its confirmation often reached with great delay. By whole exome sequencing, we unraveled the presence of pathogenic variants affecting genes already known to be involved in DBA pathogenesis (RPL5 and RPS19) in three patients with otherwise uncertain clinical diagnosis, and provided new insights on DBA genotype-phenotype correlations. Remarkably, the RPL5 c.482del frameshift mutation has never been reported before, whereas the RPS19 c.3G>T missense mutation, although previously described in a 2-month-old DBA patient without malformations and refractory to steroid therapy, was detected here in the mosaic state in different bodily tissues for the first time in DBA patients.

Disease-specific hematopoietic stem cell transplantation in children with inherited bone marrow failure syndromes.

Hematopoietic stem cell transplantation (HSCT) using an optimized conditioning regimen is essential for the long-term survival of patients with inherited bone marrow failure syndromes (IBMFS). We report HSCT in 24 children with Fanconi anemia (FA, n = 12), Diamond-Blackfan anemia (DBA, n = 7), and dyskeratosis congenita (DC, n = 5) from a single HSCT center. The graft source was peripheral blood stem cells (n = 19) or cord blood stem cells (n = 5). FA and DC patients received reduced-intensity conditioning, while DBA patients had myeloablative conditioning. The median numbers of infused mononuclear cells and CD34+ cells were 14.20 × 108/kg and 4.3 × 106/kg, respectively. The median time for neutrophil and platelet recovery was 12 and 18 days, respectively. Complete donor engraftment was achieved in 23 of 24 patients. There was one primary graft failure. During a median follow-up of 27.5 months (range, 2-130 months), the overall survival in all patients was 95.8%. The incidence of grade II-III acute graft versus host disease (GvHD) and chronic GvHD was 29.2% and 16.7%, respectively. We conclude that HSCT can be a curative option for patients with IBMFS. Modification of the conditioning regimen based on the type of disease may lead to encouraging long-term outcomes.

Genetic Information-Seeking Behaviors and Knowledge among Family Members and Patients with Inherited Bone Marrow Failure Syndromes.

Inherited bone marrow failure syndromes (IBMFS) including Fanconi anemia, dyskeratosis congenita, Diamond-Blackfan anemia, and Shwachman-Diamond syndrome are rare genetic disorders characterized by hematologic complications and increased risk of cancer. Patients and their families likely experience obstacles in obtaining sufficient health information given their disorders' rarity. To investigate this possibility, we examined information-seeking behaviors and levels of general and disorder-specific genetic knowledge among 315 members of 174 families with an IBMFS, and how information-seeking behaviors and socio-demographic factors may be associated with their genetic knowledge. Cross-sectional survey data indicated that participants were most likely to have ever used the Internet or healthcare providers for genetic information. On average, participants correctly answered 57 % of items assessing general genetic knowledge and 49-59 % of disorder-specific knowledge items. Greater knowledge was associated with greater education and ever experiencing genetic counseling, attending a scientific meeting, and seeking information from the Internet and scientific literature. Among families with Fanconi anemia (whose family support organization has the longest history of providing information), greater disorder-specific genetic knowledge was also associated with seeking information from support groups and other affected families. Results suggest that families with IBMFS have uncertainty regarding genetic aspects of their disorder, and highlight potential channels for delivering educational resources.

Reduced anti-Müllerian hormone levels in males with inherited bone marrow failure syndromes.

Fanconi anemia (FA), dyskeratosis congenita-related telomere biology disorders (DC/TBD), and Diamond-Blackfan anemia (DBA) are inherited bone marrow failure syndromes (IBMFS) with high risks of bone marrow failure, leukemia, and solid tumors. Individuals with FA have reduced fertility. Previously, we showed low levels of anti-Müllerian hormone (AMH), a circulating marker of ovarian reserve, in females with IBMFS. In males, AMH may be a direct marker of Sertoli cell function and an indirect marker of spermatogenesis. In this study, we assessed serum AMH levels in pubertal and postpubertal males with FA, DC/TBD, or DBA and compared this with their unaffected male relatives and unrelated healthy male volunteers. Males with FA had significantly lower levels of AMH (median: 5 ng/mL, range: 1.18-6.75) compared with unaffected male relatives (median: 7.31 ng/mL, range: 3.46-18.82, P = 0.03) or healthy male volunteers (median: 7.66 ng/mL, range: 3.3-14.67, P = 0.008). Males with DC/TBD had lower levels of AMH (median: 3.76 ng/mL, range: 0-8.9) compared with unaffected relatives (median: 5.31 ng/mL, range: 1.2-17.77, P = 0.01) or healthy volunteers (median: 5.995 ng/mL, range: 1.57-14.67, P < 0.001). Males with DBA had similar levels of AMH (median: 3.46 ng/mL, range: 2.32-11.85) as unaffected relatives (median: 4.66 ng/mL, range: 0.09-13.51, P = 0.56) and healthy volunteers (median: 5.81 ng/mL, range: 1.57-14.67, P = 0.10). Our findings suggest a defect in the production of AMH in postpubertal males with FA and DC/TBD, similar to that observed in females. These findings warrant confirmation in larger prospective studies.

Clonal hematopoiesis in children with predisposing conditions.

Clonal hematopoiesis in children and young adults differs from that occuring in the older adult population. A variety of stressors drive this phenomenon, sometimes independent of age-related processes. For the purposes of this review, we adopt the term clonal hematopoiesis in predisposed individuals (CHIPI) to differentiate it from classical, age-related clonal hematopoiesis of indeterminate potential (CHIP). Stress-induced CHIPI selection can be extrinsic, such as following immunologic, infectious, pharmacologic, or genotoxic exposures, or intrinsic, involving germline predisposition from inherited bone marrow failure syndromes. In these conditions, clonal advantage relates to adaptations allowing improved cell fitness despite intrinsic defects affecting proliferation and differentiation. In certain contexts, CHIPI can improve competitive fitness by compensating for germline defects; however, the downstream effects of clonal expansion are often unpredictable - they may either counteract the underlying pathology or worsen disease outcomes. A more complete understanding of how CHIPI arises in young people can lead to the definition of preleukemic states and strategies to assess risk, surveillance, and prevention to leukemic transformation. Our review summarizes current research on stress-induced clonal dynamics in individuals with germline predisposition syndromes.