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Comprehensive annual screening reduces cancer-related mortality in Li-Fraumeni syndrome (LFS), a cancer-prone disorder caused by pathogenic germline TP53 variants. Blood tests at months 4 and 8 between annual screening are recommended but their effectiveness in early cancer detection has not been established. Interim blood counts and inflammatory biomarkers were evaluated in 132 individuals with LFS (112 adults, 87 female, median age 36 years [range 3–68], median follow-up 37 months [range 2–70]) and test abnormalities were observed in 225 (35%). Thirteen cancers in 12 individuals were diagnosed between annual screenings but only one cancer (colorectal adenocarcinoma) was diagnosed due to an abnormal interim blood test. Fisher’s exact test and generalized estimating equation models found no statistical associations between cancer diagnoses and any test abnormality. Four- and 8-monthly interim screening blood tests may not be of independent benefit for cancer detection in LFS, but annual cancer screening and personalized follow-up remain essential.

Li-Fraumeni Syndrome (LFS) is characterized by risk of multiple primary malignancies in diverse sites, pediatric onset, near complete penetrance by age 70 years, limited options for prevention, and substantial uncertainty regarding disease manifestation and prognosis. Forty-five families, including 117 individuals aged 13–81 years, enrolled in the US National Cancer Institute’s Li-Fraumeni Syndrome Study completed 66 interviews regarding their LFS experiences. An interdisciplinary team used modified grounded theory to examine family distress regarding expectations of loss and change due to likely cancer diagnoses, and the consequences of this likelihood across physical, social, and emotional domains. Disease-free periods were characterized by fearful anticipation of diagnosis or recurrence, uncertainty regarding post-treatment quality of life, and planning for shifts in family dynamics to enable caregiving. The chronicity of waiting for these changes incited dread and inhibited effective coping with the pragmatic, emotional, and existential challenges of the syndrome. Consequently, families reported high burden on roles and resources and limited guidance to prepare for, or achieve resolution with, grief. Anticipatory loss, the experience of bereavement prior to an expected change, distinguishes hereditary cancer risk from a sporadic diagnosis. Such grief is often incomplete in impact or meaning, subjected to rapid or profound change as conditions worsen, and poorly understood. In this study, losses were compounded by profound uncertainty, a chronic feature of LFS, which compromised mourning. Long-term engagement of mental health providers with bereavement training, in partnership with genetics providers, can provide invaluable educational and psychological support to families as they navigate these implacable challenges.

Li-Fraumeni syndrome (LFS) is a rare hereditary cancer syndrome associated with an autosomal-dominant mutation inheritance in the TP53 tumor suppressor gene and a wide spectrum of cancer diagnoses. The previously developed R package, LFSPRO, is capable of estimating the risk of an individual being a TP53 mutation carrier. However, an accurate estimation of the penetrance of different cancer types in LFS is crucial to improve the clinical characterization and management of high-risk individuals. Here, we developed a competing risk-based statistical model that incorporates the pedigree structure efficiently into the penetrance estimation and corrects for ascertainment bias while also increasing the effective sample size of this rare population. This enabled successful estimation of TP53 penetrance for three LFS cancer types: breast (BR), sarcoma (SA), and others (OT), from 186 pediatric sarcoma families collected at MD Anderson Cancer Center (Houston, TX). Penetrance validation was performed on a combined dataset of two clinically ascertained family cohorts with cancer to overcome internal bias in each (total number of families = 668). The age-dependent onset probability distributions of specific cancer types were different. For breast cancer, the TP53 penetrance went up at an earlier age than the reported BRCA1/2 penetrance. The prediction performance of the penetrance estimates was validated by the combined independent cohorts (BR = 85, SA = 540, and OT = 158). Area under the ROC curves (AUC) were 0.92 (BR), 0.75 (SA), and 0.81 (OT). The new penetrance estimates have been incorporated into the current LFSPRO R package to provide risk estimates for the diagnosis of breast cancer, sarcoma, or other cancers. Significance: These findings provide specific penetrance estimates for LFS-associated cancers, which will likely impact the management of families at high risk of LFS. See related article by Shin et al., p. 347

Li–Fraumeni syndrome (LFS) is a rare autosomal dominant cancer predisposition syndrome with exceptionally high lifetime cancer risks, caused primarily by germline TP53 variants. Early-onset breast cancer is the most common cancer in women with LFS. Associations between female reproductive factors and breast cancer risk have been widely studied in the general population and BRCA1/2 mutation carriers but not in LFS. We evaluated whether reproductive factors are associated with breast cancer in LFS. Questionnaire data were collected for 152 women with confirmed germline TP53 variants enrolled in the National Cancer Institute's LFS study (NCT01443468); of which, 85 had breast cancer, confirmed by pathology/medical reports. Fisher's exact test and Cox proportional hazards were used to calculate the effect of reproductive factors on breast cancer risk. Lifetime breastfeeding for at least 7 months was associated with lower breast cancer risk (hazard ratio [HR] 0.57, p = 0.05). Parity did not independently change breast cancer risk (HR 1.08, p = 0.8) but suggested an increased risk with older age at first live birth (HR 2.14, p = 0.05). Age at menarche (HR 1.09, p = 0.24) and use of oral contraceptives (HR 0.88; p = 0.7) did not significantly affect breast cancer risk. In this first study of reproductive factors and breast cancer in women with LFS, breastfeeding was observed to be protective against breast cancer risk, especially with at least 7 months of lifetime breastfeeding. Older age at first live birth was suggested to slightly increase breast cancer risk. Larger prospective studies of reproductive factors are warranted in women with LFS before making definitive clinical recommendations.

Background Pediatric cancers are the leading cause of death by disease in children despite improved survival rates overall. The contribution of germline genetic susceptibility to pediatric cancer survivors has not been extensively characterized. We assessed the frequency of pathogenic or likely pathogenic (P/LP) variants in 5451 long-term pediatric cancer survivors from the Childhood Cancer Survivor Study. Methods Exome sequencing was conducted on germline DNA from 5451 pediatric cancer survivors (cases who survived ≥5 years from diagnosis; n = 5105 European) and 597 European cancer-free adults (controls). Analyses focused on comparing the frequency of rare P/LP variants in 237 cancer-susceptibility genes and a subset of 60 autosomal dominant high-to-moderate penetrance genes, for both case-case and case-control comparisons. Results Of European cases, 4.1% harbored a P/LP variant in high-to-moderate penetrance autosomal dominant genes compared with 1.3% in controls (2-sided P = 3 × 10-4). The highest frequency of P/LP variants was in genes typically associated with adult onset rather than pediatric cancers, including BRCA1/2, FH, PALB2, PMS2, and CDKN2A. A statistically significant excess of P/LP variants, after correction for multiple tests, was detected in patients with central nervous system cancers (NF1, SUFU, TSC1, PTCH2), Wilms tumor (WT1, REST), non-Hodgkin lymphoma (PMS2), and soft tissue sarcomas (SDHB, DICER1, TP53, ERCC4, FGFR3) compared with other pediatric cancers. Conclusion In long-term pediatric cancer survivors, we identified P/LP variants in cancer-susceptibility genes not previously associated with pediatric cancer as well as confirmed known associations. Further characterization of variants in these genes in pediatric cancer will be important to provide optimal genetic counseling for patients and their families.

Diamond-Blackfan anemia (DBA) is a ribosomopathy of variable expressivity and penetrance characterized by red cell aplasia, congenital anomalies, and predisposition to certain cancers, including early-onset colorectal cancer (CRC). DBA is primarily caused by a dominant mutation of a ribosomal protein (RP) gene, although approximately 20% of patients remain genetically uncharacterized despite exome sequencing and copy number analysis. Although somatic loss-of-function mutations in RP genes have been reported in sporadic cancers, with the exceptions of 5q-myelodysplastic syndrome (RPS14) and microsatellite unstable CRC (RPL22), these cancers are not enriched in DBA. Conversely, pathogenic variants in RPS20 were previously implicated in familial CRC; however, none of the reported individuals had classical DBA features. We describe two unrelated children with DBA lacking variants in known DBA genes who were found by exome sequencing to have de novo novel missense variants in RPS20. The variants affect the same amino acid but result in different substitutions and reduce the RPS20 protein level. Yeast models with mutation of the cognate residue resulted in defects in growth, ribosome biogenesis, and polysome formation. These findings expand the phenotypic spectrum of RPS20 mutation beyond familial CRC to include DBA, which itself is associated with increased risk of CRC.

Background Li-Fraumeni syndrome (LFS) is a highly penetrant autosomal dominant cancer predisposition disorder caused by germline TP53 pathogenic variants. Patients with LFS have increased oxidative phosphorylation capacity in skeletal muscle and oxidative stress in blood. Metformin inhibits oxidative phosphorylation, reducing available energy for cancer cell proliferation and decreasing production of reactive oxygen species that cause DNA damage. Thus, metformin may provide pharmacologic risk reduction for cancer in patients with LFS, but its safety in nondiabetic patients with germline TP53 pathogenic variants has not been documented. Methods This study assessed safety and tolerability of metformin in nondiabetic LFS patients and measured changes in metabolic profiles. Adult patients with LFS and germline TP53 variant received 14 weeks of metformin. Blood samples were obtained for measurement of serum insulin-like growth factor–1, insulin, and insulin-like growth factor binding protein 3. Hepatic mitochondrial function was assessed with fasting exhaled CO2 after ingestion of 13C-labeled methionine. Changes in serum metabolome were measured. All statistical tests were 2-sided. Results We enrolled 26 participants: 20 females and 6 males. The most common adverse events were diarrhea (50.0%) and nausea (46.2%). Lactic acidosis did not occur, and there were no changes in fasting glucose. Cumulative mean 13C exhalation was statistically significantly suppressed by metformin (P = .001). Mean levels of insulin-like growth factor binding protein 3 and insulin-like growth factor-1 were statistically significantly lowered (P = .02). Lipid metabolites and branched-chain amino acids accumulated. Conclusions Metformin was safe and tolerable in patients with LFS. It suppressed hepatic mitochondrial function as expected in these individuals. This study adds to the rationale for development of a pharmacologic risk-reduction clinical trial of metformin in LFS.

PURPOSE: Li-Fraumeni Syndrome (LFS) is an inherited tumor predisposition syndrome with lifetime cancer risks approaching 100% and evolving risk-management strategies. This study evaluated couples’ coping with LFS-related burdens. RESEARCH APPROACH: Constructivist grounded theory and anticipatory loss frameworks guided design and analysis. SAMPLE AND METHODS: Twenty-six individuals enrolled in the NCI LFS Family Study completed semi-structured interviews with their partner during annual screening visits. An interdisciplinary team completed open and focused coding to identify patterns of coping and adaptation. FINDINGS: Couples described living with ambiguous danger, a state of chronic apprehension resulting from LFS-associated uncertainties. Most couples communicated openly and alternated shouldering the burden, while others engaged in protective buffering to shield each other from distress and sustain the appearance of normalcy. INTERPRETATION: Optimally, coping reduces shared psychosocial distress, yet some strategies may inadvertently increase disconnection. IMPLICATIONS: Mental health support is critical for both partners coping with LFS, together and separately.

Early onset breast cancer is the most common malignancy in women with Li-Fraumeni syndrome, caused by germline TP53 pathogenic variants. It has repeatedly been suggested that breast tumors from TP53 carriers are more likely to be HER2+ than those of noncarriers, but this information has not been incorporated into variant interpretation models for TP53. Breast tumor pathology is already being used quantitatively for assessing pathogenicity of germline variants in other genes, and it has been suggested that this type of evidence can be incorporated into current American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) guidelines for germline variant classification. Here, by reviewing published data and using internal datasets separated by different age groups, we investigated if breast tumor HER2+ status has utility as a predictor of TP53 germline variant pathogenicity, considering age at diagnosis. Overall, our results showed that the identification of HER2+ breast tumors diagnosed before the age of 40 can be conservatively incorporated into the current TP53-specific ACMG/AMP PP4 criterion, following a point system detailed in this manuscript. Further larger studies will be needed to reassess the value of HER2+ breast tumors diagnosed at a later age.

Dyskeratosis congenita (DC) is an inherited bone marrow failure and cancer susceptibility syndrome caused by germline mutations in telomere biology genes. Germline mutations in DKC1, which encodes the protein dyskerin, cause X-linked recessive DC. Because of skewed X-chromosome inactivation, female DKC1 mutation carriers do not typically develop clinical features of DC. This study evaluated female DKC1 mutation carriers with DC-associated phenotypes to elucidate the molecular features of their mutations, in comparison with unaffected carriers and mutation-negative female controls. All female DKC1 mutation carriers had normal leukocyte subset telomere lengths and similarly skewed X-inactivation in multiple tissue types, regardless of phenotype. We observed dyskerin expression, telomerase RNA accumulation, and pseudouridylation present in all mutation carriers at levels comparable to healthy wild-type controls. Our study suggests that mechanisms in addition to X chromosome inactivation, such as germline mosaicism or epigenetics, may contribute to DC-like phenotypes present in female DKC1 mutation carriers. Future studies are warranted to understand the molecular mechanisms associated with the phenotypic variability in female DKC1 mutation carriers, and to identify those at risk of disease. Am. J. Hematol. 91:1215-1220, 2016. © 2016 Wiley Periodicals, Inc.

BACKGROUND Li-Fraumeni syndrome (LFS) is an autosomal dominant cancer predisposition syndrome characterized by a very high lifetime cancer risk and an early age at diagnosis of a wide cancer spectrum. Precise estimates for the risk of first and subsequent cancers are lacking. METHODS The National Cancer Institute's Li-Fraumeni Syndrome Study includes families meeting the diagnostic criteria for LFS or Li-Fraumeni-like syndrome, and individuals with a germline TP53 mutation, choroid plexus carcinoma, adrenocortical carcinoma, or ≥3 cancers. Herein, we estimated the cumulative risk and annual hazards for first and second cancers among TP53 mutation carriers (TP53 positive [TP53+]) using MATLAB statistical software. RESULTS This study evaluated 286 TP53+ individuals from 107 families. The cumulative cancer incidence was 50% by age 31 years among TP53+ females and 46 years among males, and nearly 100% by age 70 years for both sexes. Cancer risk was highest after age 20 years for females, mostly due to breast cancer, whereas among males the risk was higher in childhood and later adulthood. Among females, the cumulative incidence rates by age 70 years for breast cancer, soft tissue sarcoma, brain cancer, and osteosarcoma were 54%, 15%, 6%, and 5%, respectively. Among males, the incidence rates were 22%, 19%, and 11%, respectively, for soft tissue sarcoma, brain cancer, and osteosarcoma. Approximately 49% of those with 1 cancer developed at least another cancer after a median of 10 years. The average age-specific risk of developing a second cancer was comparable to that of developing a first cancer. CONCLUSIONS The cumulative cancer risk in TP53 + individuals was very high and varied by sex, age, and cancer type. Additional work, including prospective risk estimates, is needed to better inform personalized risk management. Cancer 2016;122:3673-81. © 2016 American Cancer Society.

Background Telomere length

On behalf of the Clinical Care Consortium for Telomere-associated Ailments (CCCTAA)., Vascular complications such as bleeding due to gastrointestinal telangiectatic anomalies, pulmonary arteriovenous malformations, hepatopulmonary syndrome, and retinal vessel abnormalities are being reported in patients with telomere biology disorders (TBDs) more frequently than previously described. The international clinical care consortium of telomere-associated ailments and family support group Dyskeratosis Congenita Outreach, Inc. held a workshop on vascular abnormalities in the TBDs at the National Cancer Institute in October 2017. Clinicians and basic scientists reviewed current data on vascular complications, hypotheses for the underlying biology and developed new collaborations to address the etiology and clinical management of vascular complications in TBDs.

Background Prior research has established that the prevalence of pathogenic/likely pathogenic (P/LP) variants across all of the American College of Medical Genetics (ACMG) Secondary Findings (SF) genes is approximately 0.8–5%. We investigated the prevalence of P/LP variants in the 24 ACMG SF v2.0 cancer genes in a family-based cancer research cohort (n = 1173) and in cancer-free ethnicity-matched controls (n = 982). Methods We used InterVar to classify variants and subsequently conducted a manual review to further examine variants of unknown significance (VUS). Results In the 24 genes on the ACMG SF v2.0 list associated with a cancer phenotype, we observed 8 P/LP unique variants (8 individuals; 0.8%) in controls and 11 P/LP unique variants (14 individuals; 1.2%) in cases, a non-significant difference. We reviewed 115 VUS. The median estimated per-variant review time required was 30 min; the first variant within a gene took significantly (p = 0.0009) longer to review (median = 60 min) compared with subsequent variants (median = 30 min). The concordance rate was 83.3% for the variants examined by two reviewers. Conclusion The 115 VUS required database and literature review, a time- and labor-intensive process hampered by the difficulty in interpreting conflicting P/LP determinations. By rigorously investigating the 24 ACMG SF v2.0 cancer genes, our work establishes a benchmark P/LP variant prevalence rate in a familial cancer cohort and controls. Electronic supplementary material The online version of this article (10.1186/s13073-018-0607-5) contains supplementary material, which is available to authorized users.

Dyskeratosis congenita (DC) is an inherited bone marrow failure syndrome caused by germline mutations in telomere biology genes. Patients have extremely short telomeres for their age and a complex phenotype including oral leukoplakia, abnormal skin pigmentation, and dysplastic nails in addition to bone marrow failure, pulmonary fibrosis, stenosis of the esophagus, lacrimal ducts and urethra, developmental anomalies, and high risk of cancer. We evaluated a patient with features of DC, mood dysregulation, diabetes, and lack of pubertal development. Family history was not available but genome-wide genotyping was consistent with consanguinity. Whole exome sequencing identified 82 variants of interest in 80 genes based on the following criteria: homozygous

Dyskeratosis congenita (DC) is an inherited bone marrow failure syndrome and the prototypic telomere biology disorder (TBD). Leukocyte telomere length (TL) less than the first percentile for age, measured by flow cytometry with in situ hybridization (flow FISH), is diagnostic of DC. Androgens are a therapeutic option for DC/TBD-associated bone marrow failure (BMF). One report has shown an apparent increase in TL in patients while on treatment with the attenuated androgen danazol. The aim of this study was to compare TL over time in 10 androgen-treated and 16 untreated patients with DC. All subjects were enrolled in institutional review board-approved longitudinal cohort studies of inherited BMF. TL in 6-panel leukocyte subsets was measured by flow FISH. Generalized estimating equations (GEE) methodology was used to compare TL changes over time between groups. Unadjusted analyses showed annual median total lymphocyte TL attrition of -62 base pairs/year (bp/y) in androgen-treated patients with DC compared with -76 bp/y in untreated DC patients (P = .71). Longitudinal analysis using a GEE model, adjusted for age at sample collection, showed no statistically significant difference in TL change over time between treated and untreated patients (P = .24). The results were similar for each individual leukocyte subset evaluated. In summary, our data show the expected age-associated longitudinal telomere shortening in patients with DC, irrespective of androgen therapy. Caution is warranted when recommending androgen therapy for non-BMF manifestations of DC or TBDs until the biological mechanisms are better understood.

Several methods have been employed to measure telomere length (TL) in human studies. It has been difficult to directly compare the results from these studies because of differences in the laboratory techniques and output parameters. We compared TL measurements (TLMs) by the three most commonly used methods, quantitative polymerase chain reaction (qPCR), flow cytometry with fluorescence in situ hybridization (flow FISH) and Southern blot, in a cohort of patients with the telomere biology disorder dyskeratosis congenita (DC) and in their unaffected relatives (controls). We observed a strong correlation between the Southern blot average TL and the flow FISH total lymphocyte TL in both the DC patients and their unaffected relatives (R2 of 0.68 and 0.73, respectively). The correlation between the qPCR average TL and that of the Southern blot method was modest (R2 of 0.54 in DC patients and of 0.43 in unaffected relatives). Similar results were noted when comparing the qPCR average TL and the flow FISH total lymphocyte TL (R2 of 0.49 in DC patients and of 0.42 in unaffected relatives). In conclusion, the strengths of the correlations between the three widely used TL assays (qPCR, flow FISH, and Southern blot) were significantly different. Careful consideration is warranted when selecting the method of TL measurement for research and for clinical studies.

Importance Establishment of an optimal cancer surveillance program is important to reduce cancer-related morbidity and mortality in individuals with Li-Fraumeni syndrome, a rare, highly penetrant cancer predisposition syndrome. Objective To determine the feasibility and efficacy of a comprehensive cancer screening regimen in Li-Fraumeni syndrome, using multiple radiologic techniques, including rapid whole-body magnetic resonance imaging (MRI) and laboratory measurements. Design, Setting, and Participants Baseline evaluation of a prospective cancer screening study was conducted from June 1, 2012, to July 30, 2016, at the National Cancer Institute, National Institutes of Health (an academic research facility). Participants included 116 individuals with Li-Fraumeni syndrome with a germline TP53 pathogenic variant who were aged 3 years or older at the time of baseline screening and had not received active cancer therapy at least 6 months prior to screening. Main Outcomes and Measures Detection of prevalent cancer with multimodal screening techniques and the need for additional evaluation. Results Of the 116 study participants, 77 (66.4%) were female; median age was 37.6 years (range, 3-68 years). Baseline cancer screening led to the diagnosis of cancer in 8 (6.9%) individuals (2 lung adenocarcinomas, 1 osteosarcoma, 1 sarcoma, 1 astrocytoma, 1 low-grade glioma, and 2 preinvasive breast cancers [ductal carcinoma in situ]); all but 1 required only resection for definitive treatment. A total of 40 (34.5%) participants required additional studies to further investigate abnormalities identified on screening, with 32 having incidental, benign, or normal findings, resulting in a false-positive rate of 29.6%. Non-MRI techniques, including baseline blood tests, abdominal ultrasonography in children, mammography, and colonoscopy, did not lead to a diagnosis of prevalent cancer in our cohort. Conclusions and Relevance This study describes the establishment and feasibility of an intensive cancer surveillance protocol for individuals with Li-Fraumeni syndrome. Prevalent cancers were detected at an early stage with baseline whole-body, brain, and breast MRI. Prospective screening of the participants is under way.

ImportanceThere are limited guidelines for clinical management in Li-Fraumeni syndrome, a multi-organ cancer predisposition condition. Whole body magnetic resonance imaging may play a role in surveillance of this high risk population.ObjectiveTo assess the clinical utility of whole body magnetic resonance imaging in germline TP53 mutation carriers at baseline.Data SourcesClinical and research surveillance cohorts were identified through the Li-Fraumeni Exploration Research Consortium.Study selectionCohorts that incorporated whole body magnetic resonance imaging for individuals with germline TP53 mutations were included.Data extraction and synthesisData was extracted by investigators from each cohort independently and synthesized by two investigators. Random effects meta-analysis methods were used to estimate proportions. Main outcomes and measuresThe proportion of participants at baseline in whom a lesion was detected that required follow up and in whom a new primary malignancy was detected. ResultsA total 578 participants from 13 cohorts were included in the analysis. Two hundred twenty-five lesions requiring clinical follow up were detected by whole body magnetic resonance imaging in 173 participants. Sixty-one lesions were diagnosed in 54 individuals as either benign or malignant neoplasms. Overall, 42 cancers were identified in 39 individuals, with 35 new localized cancers treated with curative intent. The overall detection rate for new localized primary cancers was 7% (95% Confidence Interval 5-9%).Conclusions and relevanceThese data suggest clinical utility in baseline whole body magnetic resonance imaging in TP53 germline mutation carriers, and may form an integral part of baseline clinical risk management in this high-risk population.

Telomeres, long nucleotide repeats and a protein complex at chromosome ends, shorten with each cell division and are susceptible to oxidative damage. Quantitative PCR (qPCR) is a widely-used technique to measure relative telomere length (RTL) in DNA samples but is challenging to optimize and significant lab-to-lab variability has been reported. In this study, we evaluated factors that may contribute to qPCR RTL measurement variability including DNA extraction methods, methods used for removing potential residual PCR inhibitors, sample storage conditions, and sample location in the PCR plate. Our results show that the DNA extraction and purification techniques, as well as sample storage conditions introduce significant variability in qPCR RTL results. We did not find significant differences in results based on sample location in the PCR plate or qPCR instrument used. These data suggest that lack of reproducibility in published association studies of RTL could be, in part, due to methodological inconsistencies. This study illustrates the importance of uniform sample handling, from DNA extraction through data generation and analysis, in using qPCR to determine RTL.

BackgroundDiamond-Blackfan anaemia (DBA) is an inherited bone marrow failure syndrome (IBMFS) characterised by erythroid hypoplasia. It is associated with congenital anomalies and a high risk of developing specific cancers. DBA is caused predominantly by autosomal dominant pathogenic variants in at least 15 genes affecting ribosomal biogenesis and function. Two X-linked recessive genes have been identified.ObjectivesWe aim to identify the genetic aetiology of DBA.MethodsOf 87 families with DBA enrolled in an institutional review board-approved cohort study (ClinicalTrials.gov Identifier:NCT00027274), 61 had genetic testing information available. Thirty-five families did not have a known genetic cause and thus underwent comprehensive genomic evaluation with whole exome sequencing, deletion and CNV analyses to identify their disease-associated pathogenic variant. Controls for functional studies were healthy mutation-negative individuals enrolled in the same study.ResultsOur analyses uncovered heterozygous pathogenic variants in two previously undescribed genes in two families. One family had a non-synonymous variant (p.K77N) inRPL35; the second family had a non-synonymous variant (p. L51S) inRPL18. Both of these variants result in pre-rRNA processing defects. We identified heterozygous pathogenic variants in previously known DBA genes in 16 of 35 families. Seventeen families who underwent genetic analyses are yet to have a genetic cause of disease identified.ConclusionsOverall, heterozygous pathogenic variants in ribosomal genes were identified in 44 of the 61 families (72%). De novo pathogenic variants were observed in 57% of patients with DBA. Ongoing studies of DBA genomics will be important to understand this complex disorder.

Pulmonary arteriovenous malformations are under-recognized in telomere biology disorders and present diagnostic and therapeutic challenges.

1530Background: Li-Fraumeni syndrome (LFS) is an autosomal dominant inherited cancer predisposition syndrome associated with germline pathogenic variants in TP53. It is characterized by early-onset...

The inherited bone marrow failure syndromes (IBMFS) are a rare yet clinically important cause of neonatal hematological and non-hematological manifestations. Many of these syndromes, such as Fanconi anemia, dyskeratosis congenita and Diamond-Blackfan anemia, confer risks of multiple medical complications later in life, including an increased risk of cancer. Some IBMFS may present with cytopenias in the neonatal period whereas others may present only with congenital physical abnormalities and progress to pancytopenia later in life. A thorough family history and detailed physical examination are integral to the work-up of any neonate in whom there is a high index of suspicion for an IBMFS. Correct detection and diagnosis of these disorders is important for appropriate long-term medical surveillance and counseling not only for the patient but also for appropriate genetic counselling of their families regarding recurrence risks in future children and generations.

Introduction: Diamond-Blackfan anemia (DBA) is a rare inherited bone marrow failure syndrome (IBMFS) characterized by erythroid hypoplasia. It is associated with a number of congenital anomalies and a high risk of developing specific cancers. DBA is caused by germline mutations or deletions in genes affecting ribosomal biogenesis and function, with autosomal dominant or X-linked recessive patterns of inheritance. The most commonly mutated gene is RPS19, seen in approximately 25% of patients. About 45% of DBA families have no known disease-causing pathogenic variant. Methods: Affected and unaffected individuals from families with DBA were ascertained through the IRB-approved NCI IBMFS retrospective/prospective cohort study (ClinicalTrials.gov Identifier: NCT00027274). Study participants completed detailed family and medical history questionnaires, medical records were reviewed, and a subset of families underwent clinical evaluations at the NIH Clinical Center. DBA patients enrolled prior to 2014 underwent routine clinical mutation testing for the established DBA genes; beginning in 2014, DBA patient samples (buccal and blood DNA) were evaluated by whole exome sequencing (WES) for mutation identification. We incorporated WES with deletion analyses and copy number variant (CNV) assessment to uncover the genetic changes causative of DBA. Deletion analyses performed included SNP genotyping and array comparative genomic hybridization. Functional effects of the genetic variants were proven by pre-rRNA processing defect analysis by Northern blot. Controls for functional studies were healthy mutation-negative individuals from the IBMFS study. Results: Genetic testing information was available in 61 of the 87 families with DBA enrolled in the IBMFS study. Thirty-five of the 61 families did not have a known genetic cause at enrollment. Our combined approach of WES, deletion and CNV analyses identified the causative pathogenic variant in 18 of the 35 (51%) uncharacterized DBA families. We discovered pathogenic variants in two previously undescribed genes in two DBA families. One family had a nonsynonymous variant (p.K77N) in RPL35; the second family had a nonsynonymous variant (p. L51S) in RPL18. Both of these variants result in characteristic pre-rRNA processing defects. Our analyses also uncovered germline mosaic deletions in known DBA genes in both buccal and blood cells of two patients from two different families. One was a 1.8 Mb mosaic deletion in chromosome 15 including RPS17; the other was a large 2.5 Mb mosaic deletion on chromosome 3 including RPL35A. In addition to these findings, we found variants in previously known DBA-associated ribosomal genes in 14 of the 35 families. We further evaluated the genomic characteristics of the entire DBA cohort. Pathogenic variants in ribosomal DBA genes were found in a total of 44 of the 61 families (72%) on whom genetic testing information and/or biospecimens were available. RPS19 was the most frequently mutated gene and accounted for 36% of families, followed by RPL35A and RPS26, accounting for 14% and 11% each, respectively. Notably, 30% of the variation in disease-causing genes in our cohort was due to a single copy or mosaic gene deletion. We had complete parental testing and inheritance information on 23 (52%) of the 44 families whose gene was identified. Ten of the 23 (43%) had an inherited mutation and 13 (57%) had a de novo change in the causative gene (both parents were negative for the affected child's disease-associated mutation). At this time, 17 of 61 families tested (28%) do not have a characterized disease-associated mutation. Conclusion: This efficient comprehensive genomic approach was the basis for our discovery of two novel causes of DBA, characterization of ribosomal gene deletions not previously described to be disease-associated, and of DBA-associated germline mosaicism. We identified the disease-associated mutations in 51% (18 of 35) of our families without a known genetic cause of DBA. A total of 74% (44 of 61) of our families are now genetically characterized. Our comprehensive approach appears to provide more genomic information than other methods since pathogenic variants of DBA genes have been reported previously in about 55% of DBA patients. Disclosures No relevant conflicts of interest to declare.

1526Background: Li-Fraumeni syndrome (LFS) is a rare autosomal dominant cancer predisposition syndrome primarily caused by germline TP53 mutations. LFS is associated with very high lifetime cancer risk and early onset of a wide range of cancers. Cancer surveillance is challenging given the tumor spectrum, although an MRI-based regimen has shown promise. An important aim of NCI’s LFS cohort study (NCT01443468) is to establish an effective cancer-screening regimen. Methods: Individuals with a germline TP53 mutation were eligible for screening with annual rapid sequence whole-body (WB) MRI, brain MRI, and breast MRI if applicable, colonoscopy every 3 years, and blood tests every 4 months; children < 17 years also have abdominal ultrasound every 4 months. Here we report the findings at baseline screening of the first 100 participants. Results: Twenty of the 100 WB MRIs had abnormalities requiring additional imaging. Subsequent biopsies in 3 individuals led to the diagnosis of 1 stage Ib lung cancer and 1 oste...