TP53_PROF: a machine learning model to predict impact of missense mutations in TP53

Correctly identifying the true driver mutations in a patient’s tumor is a major challenge in precision oncology. Most efforts address frequent mutations, leaving medium- and low-frequency variants mostly unaddressed. For TP53, this identification is crucial for both somatic and germline mutations, with the latter associated with the Li-Fraumeni syndrome (LFS), a multiorgan cancer predisposition. We present TP53_PROF (prediction of functionality), a gene specific machine learning model to predict the functional consequences of every possible missense mutation in TP53, integrating human cell- and yeast-based functional assays scores along with computational scores. Variants were labeled for the training set using well-defined criteria of prevalence in four cancer genomics databases. The model’s predictions provided accuracy of 96.5%. They were validated experimentally, and were compared to population data, LFS datasets, ClinVar annotations and to TCGA survival data. Very high accuracy was shown through all methods of validation. TP53_PROF allows accurate classification of TP53 missense mutations applicable for clinical practice. Our gene specific approach integrated machine learning, highly reliable features and biological knowledge, to create an unprecedented, thoroughly validated and clinically oriented classification model. This approach currently addresses TP53 mutations and will be applied in the future to other important cancer genes.

Pediatric adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is a rare endocrine malignancy of the adrenal gland with an unfavorable prognosis. It is rare in the pediatric population, with an incidence of 0.2-0.3 patients per million in patients under 20 years old. It is primarily associated with Li-Fraumeni and Beckwith-Wiedemann tumor predisposition syndromes in children. The incidence of pediatric ACC is 10-15fold higher in southern Brazil due to a higher prevalence of TP53 mutation associated with Li-Fraumeni syndrome in that population. Current treatment protocols are derived from adult ACC and consist of surgery and/or chemotherapy with etoposide, doxorubicin, and cisplatin (EDP) with mitotane. Limited research has been reported on other treatment modalities for pediatric ACC, including mitotane, pembrolizumab, cabozantinib, and chimeric antigen receptor autologous cell (CAR-T) therapy.

Therapy-related Myeloid Neoplasms in Children: A Single-institute Study

Therapy-related myeloid neoplasm (t-MN) in the pediatric population is not well characterized. We studied 12 pediatric patients diagnosed with t-MN in our institution since 2006. The median age at the t-MN diagnoses was 14.8 years (range, 9 to 20 y). The primary malignancies included 9 solid tumors and 3 hematopoietic malignancies. Rhabdomyosarcoma (n=4) was the most common primary malignancy. Five of the 9 patients with solid tumors and all 3 patients with hematopoietic malignancies had primary neoplasms involving bone marrow. The median latency period was 5.2 years (range, 1.8 to 13.8 y). Thrombocytopenia was present in all patients at the t-MN diagnoses. Complete or partial monosomy of chromosome 5 or 7 were the 2 most common cytogenetic abnormalities. A quarter of patients demonstrated a genetic predisposition to t-MN: 1 with Li-Fraumeni syndrome with a germline TP53 R248Q mutation, 1 with Noonan syndrome with a somatic mutation (PTPN11 S502T), and 1 with a constitutive chromosomal translocation [t(X;9)(p22;q34)] and a germline TP53 L130V mutation. Outcomes remain poor. Two patients survived 3 and 5.1 years after hematopoietic stem cell transplantation.

Reproduction and Genetic Responsibility: An Interpretive Description of Reproductive Decision-Making for Young People With Li-Fraumeni Syndrome

The reproductive decision-making of young people (aged 15-39 years) with Li-Fraumeni syndrome (LFS), an early onset inherited cancer syndrome, has not been studied in depth. Using interpretive description methodology, we conducted semi-structured interviews with 30 young Australians (mean age 25.5 years) diagnosed with LFS or at 50% genetic risk. With reflexive thematic analysis, we show how young people's reproductive decision-making and ideals for family formation were shaped by a sense of genetic responsibility to ensure the health of future biological kin. Reproductive technology provided choices for family formation in the context of LFS and also complicated reproductive decisions, as these choices were difficult to understand, make, or carry out. We uphold that reproductive decision-making when living with LFS is a profoundly moral practice that may pose significant challenges for young people navigating their formative years. We offer genetic counseling practice recommendations to support individuals with LFS when making reproductive decisions.

A Functional Precision Medicine Pipeline Combines Comparative Transcriptomics and Tumor Organoid Modeling to Identify Bespoke Treatment Strategies for Glioblastoma

Li Fraumeni syndrome (LFS) is a hereditary cancer predisposition syndrome caused by germline mutations in TP53. TP53 is the most common mutated gene in human cancer, occurring in 30-50% of glioblastomas (GBM). Here, we highlight a precision medicine platform to identify potential targets for a GBM patient with LFS. We used a comparative transcriptomics approach to identify genes that are uniquely overexpressed in the LFS GBM patient relative to a cancer compendium of 12,747 tumor RNA sequencing data sets, including 200 GBMs. STAT1 and STAT2 were identified as being significantly overexpressed in the LFS patient, indicating ruxolitinib, a Janus kinase 1 and 2 inhibitors, as a potential therapy. The LFS patient had the highest level of STAT1 and STAT2 expression in an institutional high-grade glioma cohort of 45 patients, further supporting the cancer compendium results. To empirically validate the comparative transcriptomics pipeline, we used a combination of adherent and organoid cell culture techniques, including ex vivo patient-derived organoids (PDOs) from four patient-derived cell lines, including the LFS patient. STAT1 and STAT2 expression levels in the four patient-derived cells correlated with levels identified in the respective parent tumors. In both adherent and organoid cultures, cells from the LFS patient were among the most sensitive to ruxolitinib compared to patient-derived cells with lower STAT1 and STAT2 expression levels. A spheroid-based drug screening assay (3D-PREDICT) was performed and used to identify further therapeutic targets. Two targeted therapies were selected for the patient of interest and resulted in radiographic disease stability. This manuscript supports the use of comparative transcriptomics to identify personalized therapeutic targets in a functional precision medicine platform for malignant brain tumors.

Family Identity and Roles in the Context of Li-Fraumeni Syndrome: "No One's Like Us Mutants"

Li-Fraumeni syndrome (LFS) is a rare hereditary cancer syndrome in which individuals have a significantly increased risk of developing multiple cancers throughout the life span. An LFS diagnosis may shift the individual's sense of self and tolerance of cancer risk as they engage in cancer screening and cancer prevention activities. This study examined the impact of family identity on health decision making, communication, and role function. Forty-five families completed one or more interviews during an annual, protocol-specific cancer screening study. An interdisciplinary team analyzed 66 interviews using interpretive description and modified grounding theory. Thematically, identity emerged as an evolving construct regarding self and/or family, embedded in historical and ongoing experiences with LFS. Notions of individual and shared family identities guided decision making related to healthcare and influenced interpersonal communication and role function between supportive networks and families. Alignment between individual, family, and generational identities may shape engagement in genetic testing, risk management, and family life. Medical teams that are unequipped to address the psychosocial challenges that LFS populations face may include mental health professionals on interprofessional care teams to navigate risk management and consequential familial conflict.

A Novel Germline TP53 Mutation in a Patient With Li-Fraumeni Syndrome: Resolving a Variant of Uncertain Significance

Increasing availability of genomic testing poses new challenges to clinicians, particularly where variant interpretation from commercial sources may be equivocal. The authors report a patient with recurrent rhabdomyosarcoma and subsequent bilateral breast cancer who was found to harbor a previously undescribed germline TP53 sequence alteration annotated by the commercial laboratory as a variant of uncertain significance. By investigating publicly available databases of aggregated normal germline and malignant somatic genomic sequences, the authors conclude that this missense variant, c.476C>T (p.A159V), is a novel, pathogenic Li-Fraumeni syndrome mutation and demonstrate the utility of these resources in clinical pediatric hematology and oncology practice.

Evaluation of TP53 Variants Detected on Peripheral Blood or Saliva Testing: Discerning Germline From Somatic TP53 Variants

PURPOSE

Multigene panel testing (MGPT) identifies TP53 pathogenic or likely pathogenic (P/LP) variants in patients with diverse phenotypes, of which only one is classic Li-Fraumeni syndrome. Low variant allelic fraction (VAF) in TP53 found on germline testing may suggest aberrant clonal expansion or constitutional mosaicism. We evaluated TP53-positive probands seen in a cancer genetics program to determine germline versus somatic status.

METHODS

We reviewed TP53-positive probands from 2012 to 2019 identified by MGPT on blood or saliva (N = 84). Available VAFs were collected. Probands with a familial variant, who met Li-Fraumeni syndrome testing criteria or who carried a founder variant, were considered germline. For those with uncertain germline status, TP53 variants were further examined using ancillary data of family members and somatic tissue.

RESULTS

Of the 84 probands, 54.7% had germline variants with 33.3% meeting criteria for germline status and 21.4% confirmed through ancillary testing. Aberrant clonal expansion comprised 13.1% with clonal hematopoiesis of indeterminate potential and 2.4% with a hematologic malignancy. Constitutional mosaicism was confirmed in 8.3% probands. Definitive status could not be determined in 3.6% despite ancillary assessment, and 17.9% did not have ancillary testing.

CONCLUSION

A TP53 P/LP variant found on peripheral blood or saliva MGPT does not always originate in the germline. In a clinical cancer genetics cohort, approximately half of the patients had TP53 P/LP germline variants; these patients plus those with constitutional mosaicism require intensified surveillance. A framework of multiple strategies enables discernment of germline from constitutional mosaic and acquired variants, which is essential for appropriate management.

Revisitando la indicación de la mastectomía profiláctica contralateral en pacientes con Síndrome de Li-Fraumeni y cáncer de mama. Reporte de un caso

Objetivo: describir el caso de una paciente con Síndrome de Li-Fraumeni (SLF) y cáncer de mama, en quien se cuestionó el beneficio en la supervivencia de la mastectomía profiláctica contralateral (MPC); asimismo, se pretende hacer una discusión crítica acerca de la evidencia que soporta este procedimiento en esta población. Presentación del caso: mujer de 37 años con cáncer de mama y múltiples antecedentes familiares de cánceres de temprana aparición del espectro del SLF, en quien, durante la adyuvancia hormonal, se confirmó una variante patogénica en el gen TP53. La paciente fue presentada en la Junta Multidisciplinaria del Servicio de Mama de un Centro Oncológico de referencia en Colombia, con el fin de discutir el beneficio de la MPC. La decisión de la junta fue no realizar la MPC. Después de 30 meses de seguimiento la paciente se encuentra libre de enfermedad. Conclusión: no existe evidencia que analice, de forma particular, el impacto de la MPC en la supervivencia de las pacientes con SLF y cáncer de mama. Sin embargo, a la luz del conocimiento actual no es posible generalizar la conducta de omitir esta cirugía profiláctica. Es importante reportar los casos en los que se decida realizar u omitir este procedimiento con el fin de incrementar el cuerpo de la evidencia, dado que existen limitaciones para construir grandes cohortes o estudios experimentales exclusivos para esta alteración genética.

Clinical and molecular characterization of patients fulfilling Chompret criteria for Li-Fraumeni syndrome in Southern Brazil

Li-Fraumeni syndrome (LFS) is an autosomal dominant cancer predisposition syndrome caused by pathogenic germline variants in the TP53 gene, characterized by a predisposition to the development of a broad spectrum of tumors at an early age. The core tumors related to LFS are bone and soft tissue sarcomas, premenopausal breast cancer, brain tumors, adrenocortical carcinomas (ACC), and leukemias. The revised Chompret criteria has been widely used to establish clinical suspicion and support TP53 germline variant testing and LFS diagnosis. Information on TP53 germline pathogenic variant (PV) prevalence when using Chompret criteria in South America and especially in Brazil is scarce. Therefore, the aim of this study was to characterize patients that fulfilled these specific criteria in southern Brazil, a region known for its high population frequency of a founder TP53 variant c.1010G>A (p.Arg337His), as known as R337H. TP53 germline testing of 191 cancer-affected and independent probands with LFS phenotype identified a heterozygous pathogenic/likely pathogenic variant in 26 (13.6%) probands, both in the DNA binding domain (group A) and in the oligomerization domain (group B) of the gene. Of the 26 carriers, 18 (69.23%) were R337H heterozygotes. Median age at diagnosis of the first tumor in groups A and B differed significantly in this cohort: 22 and 2 years, respectively (P = 0.009). The present study shows the clinical heterogeneity of LFS, highlights particularities of the R337H variant and underscores the need for larger collaborative studies to better define LFS prevalence, clinical spectrum and penetrance of different germline TP53 pathogenic variants.

[Genome research project detected TP53mutation in a girl with rhabdomyosarcoma]

In this case report, a germ line genome project identified a pathogenic variant in TP53 in a three-year-old girl diagnosed with rhabdomyosarcoma. The variant causes the cancer predisposition syndrome Li-Fraumeni syndrome (LFS). The girl's family was genetically counselled, and the same variant was identified in her mother and sister. The family was afterwards offered surveillance according to national guidelines. With this report, we want to focus on cancer predisposition syndromes and to discuss the benefits regarding surveillance of children with LFS.

Identification of the TP53 p.R337H Variant in Tumor Genomic Profiling Should Prompt Consideration of Germline Testing for Li-Fraumeni Syndrome

PURPOSE

Li-Fraumeni syndrome (LFS) is rare in the worldwide population, but it is highly prevalent in the Brazilian population because of a founder mutation, TP53 p.R337H, accounting for 0.3% of south and southeastern population. Clinical criteria for LFS may not identify all individuals at risk of carrying the Brazilian founder mutation because of its lower penetrance and variable expressivity. This variant is rarely described in databases of somatic mutations. Somatic findings in tumor molecular profiling may give insight to identify individuals who might be carriers of LFS and allow the adoption of risk reduction strategies for cancer.

MATERIALS AND METHODS

We determined the frequency of the TP53 p.R337H variant in tumor genomic profiling from 755 consecutive Brazilian patients with pan-cancer. This is a retrospective cohort from January 2013 to March 2020 at a tertiary care center in Brazil.

RESULTS

The TP53 p.R337H variant was found in 2% (15 of 755) of the samples. The mutation allele frequency ranged from 30% to 91.7%. A total of seven patients were referred for genetic counseling and germline testing after tumor genomic profiling results were disclosed. All the patients who proceeded with germline testing (6 of 6) confirmed the diagnosis of LFS. Family history was available in 12 cases. Nine patients (9 of 12) did not meet LFS clinical criteria.

CONCLUSION

The identification of the TP53 p.R337H variant in tumor genomic profiling should be a predictive finding of LFS in the Brazilian population and should prompt testing for germline status confirmation.

A Mouse Homolog of a Human TP53 Germline Mutation Reveals a Lipolytic Activity of p53

The physiological effects of the many germline mutations of TP53, encoding the tumor suppressor protein p53, are poorly understood. Here we report generating a p53 R178C knockin mouse modeling the human TP53 R181C mutation, which is notable for its prevalence and prior molecular characterization. Consistent with its weak cancer penetrance in humans, homozygous p53^178C/C mice show a modest increase in tumorigenesis but, surprisingly, are lean with decreased body fat content. They display evidence of increased lipolysis and upregulation of fatty acid metabolism in their inguinal white adipose tissue (iWAT). Gene expression and chromatin immunoprecipitation sequencing (ChIP-seq) analyses show that the mutant p53 bound and trans-activated Beta-3-Adrenergic Receptor (ADRB3), a gene that is known to promote lipolysis and is associated with obesity. This study reveals that a germline mutation of p53 can affect fat metabolism, which has been implicated in cancer development.

Knockin of the mouse homolog of a human TP53 germline mutation known to cause Li-Fraumeni syndrome, a cancer predisposition disorder, results in a mouse model characterized by lower body fat content. Kang et al. show that enhancing transactivation of the lipolytic gene ADRB3 by mutant p53 contributes to this phenotype.

Specifications of the ACMG/AMP variant interpretation guidelines for germline TP53 variants

Germline pathogenic variants in TP53 are associated with Li-Fraumeni syndrome, a cancer predisposition disorder inherited in an autosomal dominant pattern associated with a high risk of malignancy, including early-onset breast cancers, sarcomas, adrenocortical carcinomas, and brain tumors. Intense cancer surveillance for individuals with TP53 germline pathogenic variants is associated with reduced cancer-related mortality. Accurate and consistent classification of germline variants across clinical and research laboratories is important to ensure appropriate cancer surveillance recommendations. Here, we describe the work performed by the Clinical Genome Resource TP53 Variant Curation Expert Panel (ClinGen TP53 VCEP) focused on specifying the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP) guidelines for germline variant classification to the TP53 gene. Specifications were developed for 20 ACMG/AMP criteria, while nine were deemed not applicable. The original strength level for the 10 criteria was also adjusted due to current evidence. Use of TP53-specific guidelines and sharing of clinical data among experts and clinical laboratories led to a decrease in variants of uncertain significance from 28% to 12% compared with the original guidelines. The ClinGen TP53 VCEP recommends the use of these TP53-specific ACMG/AMP guidelines as the standard strategy for TP53 germline variant classification.

Genetic and stochastic influences upon tumor formation and tumor types in Li-Fraumeni mouse models

p53 is the most frequently mutated gene in human cancers. Li-Fraumeni syndrome patients inheriting heterozygous p53 mutations often have a much-increased risk to develop cancer(s) at early ages. Recent studies suggest that some individuals inherited p53 mutations do not have the early onset or high frequency of cancers. These observations suggest that other genetic, environmental, immunological, epigenetic, or stochastic factors modify the penetrance of the cancerous mutant Tp53 phenotype. To test this possibility, this study explored dominant genetic modifiers of Tp53 mutations in heterozygous mice with different genetic backgrounds. Both genetic and stochastic effects upon tumor formation were observed in these mice. The genetic background of mice carrying Tp53 mutations has a strong influence upon the tissue type of the tumor produced and the number of tumors formed in a single mouse. The onset age of a tumor is correlated with the tissue type of that tumor, although identical tumor tissue types can occur at very different ages. These observations help to explain the great diversity of cancers in different Li-Fraumeni patients over lifetimes.

Genomic and Clinical Correlates of Adrenocortical Carcinoma in an Adult Patient with Li-Fraumeni Syndrome: A Case Report

Li-Fraumeni Syndrome (LFS) is defined by germline mutations of the p53 tumour suppressor gene. Adrenocortical carcinoma (ACC) is a rare aggressive malignancy that is commonly associated with LFS. Most LFS-linked ACC cases occur in children, and limited research has been dedicated to the clinical outcomes and genomics of adult cases with LFS-linked ACC. We report on a 34-year-old female who was diagnosed with three separate malignancies: stage III invasive ductal carcinoma of the right breast, metastatic ACC from the right adrenal gland, and grade 2 pleomorphic sarcoma of the left hand. Her invasive breast ductal carcinoma was treated with neoadjuvant chemotherapy, and she received a bilateral mastectomy after her LFS was confirmed with genetic blood testing. Adrenal ACC was initially treated with a right nephrectomy and adrenalectomy, followed by adjuvant mitotane and two lines of chemotherapy after disease recurrence. Her hand sarcoma was treated by second ray amputation. Further, we conducted deep next-generation sequencing of each of her unique tumour tissue samples using FoundationONE CDx. A whole-genome shot capture followed by in vitro sequencing performed by the Illumina^® HiSeq platform revealed a germline P191fs*18 TP53 mutation across all three tissue samples. This case provides insight into the genomics and clinical characteristics of LFS-linked adult-onset ACC and demonstrated that p53 mutations were preserved throughout each malignancy, without apparent treatment pressures on genomic profiling. This case reinforces the critical importance of adopting best practices for LFS, which include the implementation of highly vigilant screening and management of care in a multidisciplinary setting.

Upper Gastrointestinal Cancer Risk and Surveillance Outcomes in Li-Fraumeni Syndrome

INTRODUCTION

To assess the upper gastrointestinal (UGI) cancer risk and surveillance outcomes in Li-Fraumeni syndrome (LFS).

METHODS

Analysis of the International Agency for Research on Cancer database and a single-center adult LFS cohort.

RESULTS

UGI cancer was present in 7.2% of families and 3.9% of individuals with a pathogenic/likely pathogenic TP53 mutation in International Agency for Research on Cancer; 29% occurred before age 30. Our institutional cohort had 35 individuals (31% of the LFS cohort) with 48 cumulative upper endoscopies; 3 (8.5%) individuals had concerning UGI findings.

DISCUSSION

UGI cancer is observed in LFS. Upper endoscopy should be part of a comprehensive LFS surveillance program.

Genetic Mutations and Variants in the Susceptibility of Familial Non-Medullary Thyroid Cancer

Thyroid cancer is the most frequent endocrine malignancy with the majority of cases derived from thyroid follicular cells and caused by sporadic mutations. However, when at least two or more first degree relatives present thyroid cancer, it is classified as familial non-medullary thyroid cancer (FNMTC) that may comprise 3-9% of all thyroid cancer. In this context, 5% of FNMTC are related to hereditary syndromes such as Cowden and Werner Syndromes, displaying specific genetic predisposition factors. On the other hand, the other 95% of cases are classified as non-syndromic FNMTC. Over the last 20 years, several candidate genes emerged in different studies of families worldwide. Nevertheless, the identification of a prevalent polymorphism or germinative mutation has not progressed in FNMTC. In this work, an overview of genetic alteration related to syndromic and non-syndromic FNMTC is presented.

Mutant p53 induces Golgi tubulo-vesiculation driving a prometastatic secretome

TP53 missense mutations leading to the expression of mutant p53 oncoproteins are frequent driver events during tumorigenesis. p53 mutants promote tumor growth, metastasis and chemoresistance by affecting fundamental cellular pathways and functions. Here, we demonstrate that p53 mutants modify structure and function of the Golgi apparatus, culminating in the increased release of a pro-malignant secretome by tumor cells and primary fibroblasts from patients with Li-Fraumeni cancer predisposition syndrome. Mechanistically, interacting with the hypoxia responsive factor HIF1α, mutant p53 induces the expression of miR-30d, which in turn causes tubulo-vesiculation of the Golgi apparatus, leading to enhanced vesicular trafficking and secretion. The mut-p53/HIF1α/miR-30d axis potentiates the release of soluble factors and the deposition and remodeling of the ECM, affecting mechano-signaling and stromal cells activation within the tumor microenvironment, thereby enhancing tumor growth and metastatic colonization.

p53: 800 million years of evolution and 40 years of discovery

The evolutionarily conserved p53 protein and its cellular pathways mediate tumour suppression through an informed, regulated and integrated set of responses to environmental perturbations resulting in either cellular death or the maintenance of cellular homeostasis. The p53 and MDM2 proteins form a central hub in this pathway that receives stressful inputs via MDM2 and respond via p53 by informing and altering a great many other pathways and functions in the cell. The MDM2-p53 hub is one of the hubs most highly connected to other signalling pathways in the cell, and this may be why TP53 is the most commonly mutated gene in human cancers. Initial or truncal TP53 gene mutations (the first mutations in a stem cell) are selected for early in cancer development inectodermal and mesodermal-derived tissue-specific stem and progenitor cells and then, following additional mutations, produce tumours from those tissue types. In endodermal-derived tissue-specific stem or progenitor cells, TP53 mutations are functionally selected as late mutations transitioning the mutated cell into a malignant tumour. The order in which oncogenes or tumour suppressor genes are functionally selected for in a stem cell impacts the timing and development of a tumour.

Waiting and "weighted down": the challenge of anticipatory loss for individuals and families with Li-Fraumeni Syndrome

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.