Clonal landscape and clinical outcomes of telomere biology disorders: somatic rescuing and cancer mutations.

Telomere biology disorders (TBD), caused by pathogenic germline variants in telomere-related genes, present with multi-organ disease and a predisposition to cancer. Clonal hematopoiesis (CH) as a marker of cancer development and survival in TBD is poorly understood. Here, we characterized the clonal landscape of a large cohort of 207 TBD patients with a broad range of age and phenotype. CH occurred predominantly in symptomatic patients and in signature genes typically associated with cancers: PPM1D, POT1, TERT promoter (TERTp), U2AF1S34, and/or TP53. Chromosome 1q gain (Chr1q+) was the commonest karyotypic abnormality. Clinically, multiorgan involvement and CH in TERTp, TP53, and splicing factor genes associated with poorer overall survival. Chr1q+, and splicing factor or TP53 mutations significantly increased the risk of hematologic malignancies, regardless of the clonal burden. Chr1q+ and U2AF1S34 mutated clones were pre-malignant events associated with the secondary acquisition of mutations in genes related to hematologic malignancies. Like known effects of Chr1q+ and TP53-CH, functional studies demonstrated that U2AF1S34 mutations primarily compensated for aberrant upregulation of TP53 and interferon pathways in telomere-dysfunctional hematopoietic stem cells, highlighting the TP53 pathway as a canonical route of malignancy in TBD. In contrast, somatic POT1/PPM1D/TERTp-CH had distinct trajectories unrelated to cancer development. With implications beyond TBD, our data show that telomere dysfunction is a strong selective pressure for CH. In TBD, CH is a poor prognostic marker associated with worse overall survival. The identification of key regulatory pathways that drive clonal transformation in TBD allows the identification of patients at a higher risk of cancer development.

Germline RTEL1 Variants in Telomere Biology Disorders.

Rare germline variation in regulator of telomere elongation helicase 1 (RTEL1) is associated with telomere biology disorders (TBDs). Biallelic RTEL1 variants result in childhood onset dyskeratosis congenita and Hoyeraal-Hreidarsson syndrome whereas heterozygous individuals usually present later in life with pulmonary fibrosis or bone marrow failure. We compiled all TBD-associated RTEL1 variants in the literature and assessed phenotypes and outcomes of 44 individuals from 14 families with mono- or biallelic RTEL1 variants enrolled in clinical trial NCT00027274. Variants were classified by adapting ACMG-AMP guidelines using clinical information, telomere length, and variant allele frequency data. Compared with heterozygotes, individuals with biallelic RTEL1 variants had an earlier age at diagnosis (median age 35.5 vs. 5.1 years, p < 0.01) and worse overall survival (median age 66.5 vs. 22.9 years, p < 0.001). There were 257 unique RTEL1 variants reported in 47 publications, and 209 had a gnomAD minor allele frequency <1%. Only 38.3% (80/209) met pathogenic/likely pathogenic criteria. Notably, 8 of 209 reported disease-associated variants were benign or likely benign and the rest were variants of uncertain significance. Given the considerable differences in outcomes of TBDs associated with RTEL1 germline variants and the extent of variation in the gene, systematic functional studies and standardization of variant curation are urgently needed to inform clinical management.

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.

Liver disease and transplantation in telomere biology disorders: An international multicenter cohort.

BACKGROUND: Patients with telomere biology disorders (TBD) develop hepatic disease, including hepatitis, cirrhosis, and hepatopulmonary syndrome. No specific treatment exists for TBD-related liver disease, and the role of liver transplantation (LT) remains controversial. Our study objectives were to describe the clinical characteristics, management, and outcomes in patients with TBD-related liver disease, and their LT outcomes. METHODS: Data from 83 patients with TBD-associated liver disease were obtained from 17 participating centers in the Clinical Care Consortium of Telomere-Associated Ailments and by self-report for our retrospective, multicenter, international cohort study. RESULTS: Group A ("Advanced") included 40 patients with advanced liver disease. Of these, 20 underwent LT (Group AT). Group M ("Mild") included 43 patients not warranting LT evaluation, none of whom were felt to be medically unfit for liver transplantation. Supplemental oxygen requirement, pulmonary arteriovenous malformation, hepatopulmonary syndrome, and higher bilirubin and international normalized ratio values were associated with Group A. Other demographics, clinical manifestations, and laboratory findings were similar between groups. Six group A patients were declined for LT; 3 died on the waitlist. Median follow-up post-LT was 2.9 years (range 0.6-13.2 y). One-year survival post-LT was 73%. Median survival post-LT has not been reached. Group AT patients had improved survival by age compared to all nontransplant patients (log-rank test p = 0.02). Of 14 patients with pretransplant hypoxemia, 8 (57%) had improved oxygenation after transplant. CONCLUSIONS: LT recipients with TBD do not exhibit excessive posttransplant mortality, and LT improved respiratory status in 57%. A TBD diagnosis should not exclude LT consideration.

Benign tumors and non-melanoma skin cancers in patients with Fanconi anemia.

Fanconi anemia (FA) is an inherited bone marrow failure syndrome (IBMFS) characterized by pathogenic variants in the FA/BRCA DNA repair pathway genes. Individuals with FA have an elevated risk of developing myelodysplastic syndrome, acute myeloid leukemia, and solid tumors. Hematopoietic cell transplantation (HCT) is the most effective treatment for FA related bone marrow failure but can increase the risk of cancer development. Information on benign tumors and NMSC is lacking in patients with FA. Our objective was to characterize patients with FA enrolled in the National Cancer Institute IBMFS Study who have experienced non-melanoma skin cancers (NMSC) and/or benign tumors (BT). A total of 200 patients diagnosed with FA were enrolled in the Institutional Review Board approved study "Etiologic Investigation of Cancer Susceptibility in IBMFS: A Natural History Study" (NCT00027274). Through medical records review, we identified 30 patients with at least one NMSC, either squamous or basal cell carcinoma, or benign tumor. The remaining 170 patients comprised the control group. Out of 200 patients, 12 had NMSC, 25 had benign tumors, with an age range of 11-64 and 0-56 years, respectively. The median age at HCT was 30.5 years for NMSC patients, 9 years for benign tumor patients, and 9.1 years for controls. The most common genotype observed was FANCA, followed by FANCC and FANCI. Benign tumors spanned diverse anatomical locations. Early onset NMSC in patients with FA compared to the general population emphasizes the need for consistent monitoring in patients with FA, while the diverse anatomical locations of benign tumors underscore the importance of comprehensive surveillance for timely interventions in managing symptomatology and heightened cancer risk.

Germline biallelic BRCA2 pathogenic variants and medulloblastoma: an international cohort study.

Constitutional heterozygous pathogenic variants in genes coding for some components of the Fanconi anemia-BRCA signaling pathway, which repairs DNA interstrand crosslinks, represent risk factors for common cancers, including breast, ovarian, pancreatic and prostate cancer. A high cancer risk is also a main clinical feature in patients with Fanconi anemia (FA), a rare condition characterized by bone marrow failure, endocrine and physical abnormalities. The mainly recessive condition is caused by germline pathogenic variants in one of 21 FA-BRCA pathway genes. Among patients with FA, the highest cancer risks are observed in patients with biallelic pathogenic variants in BRCA2 or PALB2. These patients develop a range of embryonal tumors and leukemia during the first decade of life, however, little is known about specific clinical, genetic and pathologic features or toxicities. Here, we present genetic, clinical, pathological and treatment characteristics observed in an international cohort of eight patients with FA due to biallelic BRCA2 pathogenic variants and medulloblastoma (MB), an embryonal tumor of the cerebellum. Median age at MB diagnosis was 32.5 months (range 7-58 months). All patients with available data had sonic hedgehog-MB. Six patients received chemotherapy and one patient also received proton radiation treatment. No life-threatening toxicities were documented. Prognosis was poor and all patients died shortly after MB diagnosis (median survival time 4.5 months, range 0-21 months) due to MB or other neoplasms. In conclusion, MB in patients with biallelic BRCA2 pathogenic variants is a lethal disease. Future experimental treatments are necessary to help these patients.

The distribution and accumulation of the shortest telomeres in telomere biology disorders.

Individuals with telomere biology disorders (TBDs) have very short telomeres, high risk of bone marrow failure (BMF), and reduced survival. Using data from TBD patients, a mean leukocyte Southern blot telomere length (TL) of 5 kilobases (kb) was estimated as the 'telomere brink' at which human survival is markedly reduced. However, the shortest telomere, not the mean TL, signals replicative senescence. We used the Telomere Shortest Length Assay (TeSLA) to tally TL of all 46 chromosomes in blood-derived DNA and examined its relationship with TBDs. Patients (n = 18) had much shorter mean TL (TeSmTL) (2.54 ± 0.41 kb vs. 4.48 ± 0.52 kb, p < 0.0001) and more telomeres <3 kb than controls (n = 22) (70.43 ± 8.76% vs. 33.05 ± 6.93%, p < 0.0001). The proportion of ultrashort telomeres (<1.6 kb) was also higher in patients than controls (39.29 ± 10.69% vs. 10.40 ± 4.09%, p < 0.0001). TeS <1.6 kb was associated with severe (n = 11) compared with non-severe (n = 7) BMF (p = 0.027). Patients with multi-organ manifestations (n = 10) had more telomeres <1.6 kb than those with one affected organ system (n = 8) (p = 0.029). Findings suggest that TBD clinical manifestations are associated with a disproportionately higher number of haematopoietic cell telomeres reaching a telomere brink, whose length at the single telomere level is yet to be determined.

Progression of liver disease and portal hypertension in dyskeratosis congenita and related telomere biology disorders.

BACKGROUND AND AIMS: Dyskeratosis congenita (DC) and related telomere biology disorders (TBD) are characterized by very short telomeres and multisystem organ involvement including liver disease. Our study aimed to characterize baseline hepatic abnormalities in patients with DC/TBD and determine risk factors associated with liver disease progression. APPROACH AND RESULTS: A retrospective review was performed on a cohort of 58 patients (39 males) with DC/TBD who were prospectively evaluated at a single institute from 2002 to 2019. The median age at initial assessment was 18 (1.4-67.6) years, and median follow-up duration was 6 (1.4-8.2) years. Patients with autosomal or X-linked recessive inheritance and those with heterozygous TINF2 DC were significantly younger, predominantly male, and more likely to have DC-associated mucocutaneous triad features and severe bone marrow failure compared with autosomal dominant-non- TINF2 DC/TBD patients. Liver abnormality (defined at baseline assessment by laboratory and/or radiological findings) was present in 72.4% of patients with predominantly cholestatic pattern of liver enzyme elevation. Clinically significant liver disease and portal hypertension developed in 17.2% of patients during the 6-year follow-up; this progression was mainly seen in patients with recessive or TINF2 -associated DC. Significant risk factors associated with progression included the presence of pulmonary or vascular disease. CONCLUSIONS: Our experience shows a high prevalence of cholestatic pattern of liver abnormality with progression to portal hypertension in patients with DC/TBD. Presence of pulmonary and/or vascular disease in patients with recessive or TINF2 DC was an important predictor of liver disease progression, suggesting the need for increased vigilance and monitoring for complications in these patients.

Differential diagnosis of bone marrow failure syndromes guided by machine learning.

The choice to postpone treatment while awaiting genetic testing can result in significant delay in definitive therapies in patients with severe pancytopenia. Conversely, the misdiagnosis of inherited bone marrow failure (BMF) can expose patients to ineffectual and expensive therapies, toxic transplant conditioning regimens, and inappropriate use of an affected family member as a stem cell donor. To predict the likelihood of patients having acquired or inherited BMF, we developed a 2-step data-driven machine-learning model using 25 clinical and laboratory variables typically recorded at the initial clinical encounter. For model development, patients were labeled as having acquired or inherited BMF depending on their genomic data. Data sets were unbiasedly clustered, and an ensemble model was trained with cases from the largest cluster of a training cohort (n = 359) and validated with an independent cohort (n = 127). Cluster A, the largest group, was mostly immune or inherited aplastic anemia, whereas cluster B comprised underrepresented BMF phenotypes and was not included in the next step of data modeling because of a small sample size. The ensemble cluster A-specific model was accurate (89%) to predict BMF etiology, correctly predicting inherited and likely immune BMF in 79% and 92% of cases, respectively. Our model represents a practical guide for BMF diagnosis and highlights the importance of clinical and laboratory variables in the initial evaluation, particularly telomere length. Our tool can be potentially used by general hematologists and health care providers not specialized in BMF, and in under-resourced centers, to prioritize patients for genetic testing or for expeditious treatment.

Genotype-phenotype and outcome associations in patients with Fanconi anemia: the National Cancer Institute cohort.

Fanconi anemia (FA) is caused by pathogenic variants in the FA/BRCA DNA repair pathway genes, and is characterized by congenital abnormalities, bone marrow failure (BMF) and increased cancer risk. We conducted a genotype-phenotype and outcomes study of 203 patients with FA in our cohort. We compared across the genes, FA/BRCA DNA repair pathways (upstream, ID complex and downstream), and type of pathogenic variants (hypomorphic or null). We explored differences between the patients evaluated in our clinic (clinic cohort) and those who provided data remotely (field cohort). Patients with variants in upstream complex pathway had less severe phenotype [lacked VACTERL-H (Vertebral, Anal, Cardiac, Trachea-esophageal fistula, Esophageal/duodenal atresia, Renal, Limb, Hydrocephalus) association and/or PHENOS (Pigmentation, small-Head, small-Eyes, Neurologic, Otologic, Short stature) features]. ID complex was associated with VACTERL-H. The clinic cohort had more PHENOS features than the field cohort. PHENOS was associated with increased risk of BMF, and VACTERL-H with hypothyroidism. The cumulative incidence of severe BMF was 70%, solid tumors (ST) 20% and leukemia 6.5% as the first event. Head and neck and gynecological cancers were the most common ST, with further increased risk after hematopoietic cell transplantation. Among patients with FANCA, variants in exons 27-30 were associated with higher frequency of ST. Overall median survival was 37 years; patients with leukemia or FANCD1/BRCA2 variants had poorest survival. Patients with variants in the upstream complex had better survival than ID or downstream complex (p=0.001 and 0.016, respectively). FA is phenotypically and genotypically heterogeneous; detailed characterization provides new insights towards understanding this complex syndrome and guiding clinical management.

Variable Clinical Features in a Large Family With Diamond Blackfan Anemia Caused by a Pathogenic Missense Mutation in RPS19.

Introduction: Diamond Blackfan anemia (DBA) is an autosomal dominant ribosomopathy caused predominantly by pathogenic germline variants in ribosomal protein genes. It is characterized by failure of red blood cell production, and common features include congenital malformations and cancer predisposition. Mainstays of treatment are corticosteroids, red blood cell transfusions, and hematologic stem cell transplantation (HSCT). Despite a better understanding of the genotype of DBA, the biological mechanism resulting in the clinical phenotype remains poorly understood, and wide heterogeneity can be seen even within a single family as depicted here. Case Description: Thirty family members enrolled in the National Cancer Institute inherited bone marrow failure syndromes study were evaluated with detailed medical questionnaires and physical examinations, including 22 in the family bloodline and eight unrelated partners. Eight participants had been previously told they had DBA by clinical criteria. Targeted germline RPS19 testing was done on all family members. A pathogenic heterozygous missense mutation in RPS19 (p.R62Q, c.185G > A) was detected in ten family members, including one person previously presumed unaffected. Eight family members presented with macrocytic anemia in infancy; all of whom were responsive to prednisone. Four family members became treatment independent; however, one individual became transfusion-dependent 36 years later following an episode of pneumonia. One prednisone responsive individual electively discontinued steroid treatment, and lives with severe anemia. One prednisone responsive individual died at age 28 from a stroke. Two family members developed colorectal cancer in their fifties; one had never required treatment for anemia. None had major congenital anomalies. Discussion: This large family with DBA demonstrates the heterogeneity of phenotypes that can be seen within the same genotype. Most family members presented with steroid-responsive anemia in infancy and subtle congenital malformations, findings consistent with recent genotype-phenotype studies of RPS DBA. However, two family members were relatively unaffected, underscoring the importance of further studies to assess modifier genes, and epigenetic and/or environmental factors which may result in normal erythropoiesis despite underlying ribosome dysfunction. This large, multigenerational family highlights the need for individualized treatment, the importance of early cancer surveillance even in individuals with clinically mild phenotypes, and the benefit of long-term follow-up to identify late complications.

The incidence and spectrum of congenital hand differences in patients with Fanconi anaemia: analysis of 48 patients.

We analysed the spectrum of congenital hand differences in a cohort of patients with Fanconi anaemia (FA). Data of 48 FA patients at the National Cancer Institute were reviewed focusing on age at diagnosis, type and severity of limb difference and any potential association with other known clinical anomalies that are part of the FA phenotype, specifically VACTERL-H and PHENOS. Twenty-eight patients had an upper limb difference, which always included thumb hypoplasia. Twenty-three patients had bilateral upper limb differences, including varying combinations and severities of thumb hypoplasia, radial dysplasia and thumb duplication. Patients with a limb difference were diagnosed at a younger age (<2 years: 15/28 with limb anomaly versus 4/20 without a limb anomaly). However, 7/28 with limb anomalies, usually thumb hypoplasia, were not diagnosed until after 6 years of age. This study demonstrates the broad spectrum of radial ray anomalies within the FA phenotype along with the possibility of either unilateral or bilateral upper limb differences and adds further merit to consideration of screening for FA in all cases of radial ray anomaly.Level of evidence: II.

Shwachman Diamond syndrome: narrow genotypic spectrum and variable clinical features.

BACKGROUND AND OBJECTIVES: Shwachman Diamond syndrome (SDS) is an inherited bone marrow failure syndrome (IBMFS) associated with pancreatic insufficiency, neutropenia, and skeletal dysplasia. Biallelic pathogenic variants (PV) in SBDS account for >90% of SDS. We hypothesized that the SDS phenotype varies based on genotype and conducted a genotype-phenotype correlation study to better understand these complexities. METHODS: We reviewed records of all patients with SDS or SDS-like syndromes in the National Cancer Institute's (NCI) IBMFS study. Additional published SDS cohorts were reviewed and compared with the NCI cohort. RESULTS: PVs in SBDS were present in 32/47 (68.1%) participants. Biallelic inheritance of SBDS c.258 + 2T > C and c.183_184TA > CT was the most common genotype in our study (25/32, 78.1%) and published cohorts. Most patients had the SDS hallmark features of neutropenia (45/45, 100%), pancreatic insufficiency (41/43, 95.3%), and/or bony abnormalities (29/36, 80.6%). Developmental delay was common (20/34, 58.8%). Increased risk of hematologic malignancies at young ages and the rarity of solid malignancies was observed in both the NCI cohort and published studies. CONCLUSIONS: SDS is a complex childhood illness with a narrow genotypic spectrum. Patients may first present to primary care, gastroenterology, orthopedic, and/or hematology clinics. Coordinated multidisciplinary care is important for diagnosis and patient management. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00027274. IMPACT: The clinical and genetic spectrum of Shwachman Diamond Syndrome was comprehensively evaluated, and the findings illustrate the importance of a multidisciplinary approach for these complex patients. Our work reveals: 1. a narrow genotypic spectrum in SDS; 2. a low risk of solid tumors in patients with SDS; 3. patients with SDS have clinical manifestations in multiple organ systems.

Fanconi anaemia: A syndrome with distinct subgroups.

Fanconi anaemia (FA) is an inherited bone marrow failure syndrome (IBMFS) with a high cancer predisposition rate. Traditional diagnoses are made before age 10 years due to bone marrow failure (BMF) and characteristic birth defects. Up to 10% of published cases were adults at diagnosis. We hypothesized that FA subgroups diagnosed in childhood are distinct from those diagnosed as adults. We classified patients by age at diagnosis of FA as FA-PED (<18 years) or FA-ADULT (≥18 years). The National Cancer Institute IBMFS cohort included 178 FA-PED and 26 FA-ADULT cases. We compared various features; the cumulative incidences of first adverse events (severe BMF leading to haematopoietic cell transplant or death, leukaemia, or solid tumours) were compared using competing-risk analyses. FA-ADULT lacked the 'typical' FA features (birth defects and early-onset BMF or leukaemia), were mainly female, had more patients with FANCA genotype, and had or developed more head and neck squamous-cell carcinoma (HNSCC) and/or gynaecological cancers compared with FA-PED, albeit at similar ages in both subgroups. FA-ADULT is a distinct subgroup that remained unrecognized during childhood. Centres for adult haematology-oncology should consider FA diagnosis in patients with early-onset HNSCC or gynaecological cancer with or without haematologic problems.

Lipoprotein particle alterations due to androgen therapy in individuals with dyskeratosis congenita.

BACKGROUND: Dyskeratosis congenita (DC) is a telomere biology disorder associated with high rates of bone marrow failure (BMF) and other medical complications. Oral androgens are successfully used to treat BMF in DC but often have significant side effects, including elevation of serum lipids. This study sought to determine the extent to which oral androgen therapy altered lipid and lipoprotein levels. METHODS: Nuclear magnetic resonance (NMR) was used to evaluate serum lipid profiles, and lipoprotein particle number and size in nine androgen-treated individuals with DC, 45 untreated individuals with DC, 72 unaffected relatives of DC patients, and 19 untreated individuals with a different inherited BMF syndrome, Fanconi anaemia (FA). FINDINGS: Androgen-treated individuals with DC had significantly decreased serum HDL cholesterol, HDL particle number and HDL particle size (p < 0·001, p < 0·001 and p < 0·001, respectively); significantly increased serum LDL cholesterol and LDL particle number (p < 0·001, p < 0·001, respectively), decreased apoA-I and increased apoB (p < 0⋅001, p < 0⋅05 respectively) when compared with untreated individuals with DC. There were no significant lipid profile differences between untreated DC and untreated FA participants; or between untreated DC participants and their unaffected relatives. Branched chain amino acids and lipoprotein insulin resistance were not significantly different with androgen treatment. GlycA, an inflammatory acute phase reactant, was significantly increased with androgen treatment (p < 0⋅001). INTERPRETATION: Androgen treatment in DC creates an atherogenic lipoprotein profile, raising concern for the potential of elevated cardiovascular disease risk. Clinical guidelines for individuals on androgens for DC-related BMF should include cardiovascular disease monitoring. These findings could be relevant in individuals treated with androgen for other indications. FUNDING: Intramural research programs of the Division of Cancer Epidemiology and Genetics of the National Cancer Institute and National Heart, Lung, and Blood Institute.

Disease progression and clinical outcomes in telomere biology disorders.

Dyskeratosis congenita related telomere biology disorders (DC/TBDs) are characterized by very short telomeres caused by germline pathogenic variants in telomere biology genes. Clinical presentations can affect all organs, and inheritance patterns include autosomal dominant (AD), autosomal recessive (AR), X-linked (XLR), or de novo. This study examined the associations between mode of inheritance with phenotypes and long-term clinical outcomes. Two hundred thirty-one individuals with DC/TBDs (144 male, 86.6% known genotype, median age at diagnosis 19.4 years [range 0 to 71.6]), enrolled in the National Cancer Institute's Inherited Bone Marrow Failure Syndrome Study, underwent detailed clinical assessments and longitudinal follow-up (median follow-up 5.2 years [range 0 to 36.7]). Patients were grouped by inheritance pattern, considering AD-nonTINF2, AR/XLR, and TINF2 variants separately. Severe bone marrow failure (BMF), severe liver disease, and gastrointestinal telangiectasias were more prevalent in AR/XLR or TINF2 disease, whereas pulmonary fibrosis developed predominantly in adults with AD disease. After adjusting for age at DC/TBD diagnosis, we observed the highest cancer risk in AR/XLR individuals. At last follow-up, 42% of patients were deceased with a median overall survival (OS) of 52.8 years (95% confidence interval [CI] 45.5-57.6), and the hematopoietic cell or solid organ transplant-free median survival was 45.3 years (95% CI 37.4-52.1). Significantly better OS was present in AD vs AR/XLR/TINF2 disease (P < .01), while patients with AR/XLR and TINF2 disease had similar survival probabilities. This long-term study of the clinical manifestations of DC/TBDs creates a foundation for incorporating the mode of inheritance into evidence-based clinical care guidelines and risk stratification in patients with DC/TBDs. This trial was registered at www.clinicaltrials.gov as #NCT00027274.

Risk of cancer in heterozygous relatives of patients with Fanconi anemia.

PURPOSE: Fanconi anemia (FA) is a cancer-prone inherited bone marrow failure syndrome caused by biallelic pathogenic variants in one of >22 genes in the FA/BRCA DNA repair pathway. A major concern is whether the risk of cancer is increased in individuals with a single pathogenic FA gene variant. METHODS: We evaluated the risk of cancer in the relatives of patients with FA in the National Cancer Institute Inherited Bone Marrow Failure Syndrome cohort. We genotyped all available relatives and determined the rates, types of cancer and the age of patients at cancer diagnosis. We calculated the observed-to-expected (O/E) cancer ratios using data from the Surveillance, Epidemiology, and End Results Program adjusted for age, sex, and birth cohort. RESULTS: The risk of cancer was not increased among all FA relatives and FA heterozygotes (O/E ratios of 0.78 and 0.79, respectively). In particular, the risk of cancer was not increased among FANCA or FANCC heterozygotes (O/E ratios of 0.92 and 0.71, respectively). Relatives did not have typical FA cancers, and age at cancer diagnosis was not younger than expected. CONCLUSION: Understanding the risk of cancer in individuals with single pathogenic FA variants is critical for counseling and management. We did not find increased risk of cancer in these individuals. These findings do not extend to the known cancer predisposition autosomal dominant FA genes, namely BRCA1, BRCA2, PALB2, BRIP1, and RAD51C.

Genotype-cancer association in patients with Fanconi anemia due to pathogenic variants in FANCD1 (BRCA2) or FANCN (PALB2).

Fanconi anemia (FA) is the most common inherited bone marrow failure syndrome and a cancer predisposition disorder. Cancers in FA include acute leukemia and solid tumors; the most frequent solid tumor is head and neck squamous cell carcinoma. FA is a primarily autosomal recessive disorder. Several of the genes in which biallelic pathogenic variants cause FA are also autosomal monoallelic cancer predisposition genes e.g. FANCD1 (BRCA2) and FANCN (PALB2). We observed that patients with FA due to biallelic or homozygous pathogenic variants in FANCD1 and FANCN have a unique cancer association. We curated published cases plus our NCI cohort cases, including 71 patients in the FANCD1 group (94 cancers and 69 variants) and 16 patients in the FANCN group (23 cancers and 20 variants). Only patients in FANCD1 and FANCN groups had one or more of these tumors: brain tumors (primarily medulloblastoma), Wilms tumor and neuroblastoma; this is a genotype-specific cancer combination of tumors of embryonal origin. Acute leukemias, seen in all FA genotypes, also occurred in FANCD1 and FANCN group patients at young ages. In silico predictions of pathogenicity for FANCD1 variants were compared with results from a mouse embryonic stem cell-based functional assay. Patients with two null FANCD1 variants did not have an increased frequency of cancer nor earlier onset of cancer compared with those with hypomorphic variants. Patients with FA and these specific cancers should consider genetic testing focused on FANCD1 and FANCN, and patients with these genotypes may consider ongoing surveillance for these specific cancers.

Pathogenic germline IKZF1 variant alters hematopoietic gene expression profiles.

IKZF1 encodes Ikaros, a zinc finger-containing transcription factor crucial to the development of the hematopoietic system. Germline pathogenic variants in IKZF1 have been reported in patients with acute lymphocytic leukemia and immunodeficiency syndromes. Diamond-Blackfan anemia (DBA) is a rare inherited bone marrow failure syndrome characterized by erythroid hypoplasia, associated with a spectrum of congenital anomalies and an elevated risk of certain cancers. DBA is usually caused by heterozygous pathogenic variants in genes that function in ribosomal biogenesis; however, in many cases the genetic etiology is unknown. We identified a germline IKZF1 variant, rs757907717 C > T, in identical twins with DBA-like features and autoimmune gastrointestinal disease. rs757907717 C > T results in a p.R381C amino acid change in the IKZF1 Ik-x isoform (p.R423C on isoform Ik-1), which we show is associated with altered global gene expression and perturbation of transcriptional networks involved in hematopoietic system development. These data suggest that this missense substitution caused a DBA-like syndrome in this family because of alterations in hematopoiesis, including dysregulation of networks essential for normal erythropoiesis and the immune system.