How I diagnose and manage individuals at risk for inherited myeloid malignancies

Astute clinicians have reported familial clustering of myelodysplastic syndrome (MDS) and acute leukemia (AL; MDS/AL) for decades.¹  These physicians often described phenotypic features that are now known to be associated with specific genetically defined hereditary myeloid malignancy syndromes (HMMSs).²  Why, then, is the diagnosis of HMMS only now starting to be considered in the evaluation of the average adult patient with MDS/AL?

The reasons are likely several. Historically, the HMMSs, including inherited bone marrow (BM) failure syndromes (IBMFSs) like Fanconi anemia (FA), have often been part of a syndrome with features that are readily recognized in childhood.³  Thus, traditional hematology training focused on HMMS as mainly a pediatric issue. The lack of genetically defined adult-onset HMMS also limited the utility of recognizing a family history of MDS/AL for adults in most clinical scenarios. Furthermore, MDS/AL cases with usual onset in late adulthood seemed unlikely candidates for the discovery of novel hereditary cancer syndromes, which are expected to cause early-onset disease.⁴  Moreover, with MDS only incorporated into the National Cancer Institute’s Surveillance, Epidemiology, and End Results program in 2001 and limited literature on the yield of family cancer history in adult MDS/AL patients, the extent of clustering of adult MDS/AL cases has been underappreciated.⁵  These issues have led to a general resistance to the idea that inherited genetic factors contribute to a significant proportion of adult MDS/AL cases. This sentiment is changing as an increasing number of genetically defined HMMSs are discovered.

Familial platelet disorder (FPD) with associated myeloid malignancy (FPD/acute myeloid leukemia [AML]) due to inherited mutations in RUNX1 was the first HMMS to be genetically defined in 1999,⁶  followed by familial AML with CEBPA mutation in 2004.⁷  Expanding use of next-generation sequencing (NGS) contributed to the rapid discovery of 6 additional HMMSs: familial MDS/AML with GATA2 mutation,^8,9  thrombocytopenia 2 (ANKRD26),^10,11  myeloid neoplasms with germ line predisposition (ATG2B/GSKIP),¹²  familial MDS/AML with mutated DDX41,^13-16  thrombocytopenia 5 (ETV6),^17-19  and familial aplastic anemia (AA)/MDS with SRP72 mutation.²⁰  Adult-onset presentations of IBMFSs such as autosomal-dominant telomere syndromes with familial MDS/AL presentation (TERC/TERT) have also been described.^21-23  Furthermore, germ line mutations in genes traditionally thought of as solid tumor predisposition genes are increasingly identified in patients with hematopoietic malignancy (HM).^24,25 

Recognition of HMMSs in clinical care is imperative. First, a molecular diagnosis provides a precise explanation for the conditions present within an affected individual and family, which can help patients understand their specific disorder and avoid inappropriate treatments (eg, splenectomy for misdiagnosed immune thrombocytopenia [ITP] in HMMS featuring thrombocytopenia). Second, a genetic diagnosis can help avoid the use of hematopoietic stem cells (HSCs) from an asymptomatic HMMS mutation carrier.^26-31  Finally, routine clinical care now requires knowledge of HMMSs. For example, the National Comprehensive Cancer Network (NCCN) recommends surveillance for HMMSs in patients at high risk for Li-Fraumeni syndrome,³²  and clinicians ordering genetic testing of malignant cells (eg, CEBPA for AML prognosis) will encounter reports suggesting that an identified mutation may be germ line. Furthermore, the 2016 World Health Organization (WHO) classification of HMs incorporated a provisional diagnostic category for hereditary myeloid malignancies, such as AML with mutated RUNX1, prompting pathologists and clinicians to consider HMMSs when rendering diagnoses.³³  Thus, clinicians will increasingly need to identify, diagnose, and manage individuals with HMMSs.

HMMSs encompass familial MDS/AL predisposition syndromes, IBMFSs, familial myeloproliferative neoplasms (MPNs), and, more broadly, traditional hereditary cancer predisposition syndromes. A review of each HMMS is beyond the scope of this article, but the features of each syndrome are summarized in Table 1^34,35  and Figure 1 ³⁶  and have been reviewed in detail elsewhere.^37-40  In this review, we provide a practical outline for identifying and diagnosing HMMSs in hematology clinical care. We review the current evidence, or lack thereof, on how to care for individuals with known HMMS. Lastly, we outline areas of active investigation to detail the current state of the HMMS field and encourage clinicians and researchers to contribute and collaborate.

A 54-year-old woman presents to the emergency room with fever and petechiae. Her peripheral blood smear reveals a white blood cell count of 45.0 × 10⁹/L with a blast count of 15.8 × 10⁹. AML is diagnosed. An NGS panel sent for prognostication identifies 1 deleterious mutation in RUNX1 and 2 in TP53. How should this patient be evaluated for an HMMS?

We favor a stepwise, team-based screening approach. Hematologists in our practice gather a significant portion of the history needed to identify individuals with personal or family histories concerning for HMMSs during their usual histories and physical examinations. Our colleagues flag any patient with a suggestive history (Figure 2) and have a low threshold for referral to our HMMS genetics team for further evaluation. Patient-specific characteristics warranting referral include: personal or family history of longstanding cytopenias or organ-system manifestations consistent with known HMMS (Table 1; Figure 1), personal or family history of multiple HMs or other cancers, or the identification of a known or possibly deleterious mutation in an HMMS-predisposing gene on tumor testing.

Patient subgroups warranting special attention include:

Inadvertent use of HSCs from donors carrying an HMMS germ line mutation may result in poor engraftment and/or donor-derived MDS/AL.^26-31  Therefore, it is vital that all related and unrelated donors are screened for HMMSs.⁴¹  Further evaluation of the potential donor and/or recipient is warranted if a donor notes a personal or family history suggestive of an HMMS, has unexplained cytopenias, or mobilizes peripheral blood HSCs poorly.³¹ 

Molecular diagnostic testing is increasingly being used to analyze malignancies for mutations in genes, such as CEBPA, FLT3, and NPM1 in AML, to determine prognosis, guide clinical decision making, and inform therapeutic options.^42-54  Whether analyzed by classic Sanger sequencing using a gene-by-gene approach or by NGS panels, mutations identified in some genes, like CEBPA, may represent pathogenic germ line mutations.^55-57  The challenge is determining which patients with a potentially pathogenic mutation in an HMMS gene should have follow-up germ line genetic testing performed. How many of these mutations are germ line, and what are the clinical predictors that should prompt germ line analysis? The answers to these questions are not yet known but are being addressed on a research basis. For now, we recommend further evaluation using an HMMS-focused personal and family history for any patient with a somatic mutation in an HMMS-associated gene (Table 2). We perform germ line genetic testing if a pattern suggestive of an HMMS is identified and/or based on the specific gene mutated (see “Whom to test” below).

Upon referral to our inherited HM clinic, our HMMS-trained genetic counselors and physicians construct a formal 3-generation family pedigree noting the number of affected individuals, their relationships, ages at diagnosis, and specific diagnoses. We ask specific history questions (Table 2) and perform a focused physical examination to assess for the classic signs/symptoms of HMMSs, recognizing that many patients with HMMS lack the classic, most severe phenotypes. Obtaining accurate information about specific HM diagnoses, a history of mild cytopenias, or reasons for specific organ-system dysfunction, especially from family members, is challenging but critically important. Thus, we often assist in gathering laboratory records, pathology reports, and death certificates for confirmation. Finally, we assess for environmental factors or other exposures that may contribute to patient or family phenotypes.

Based on this evaluation, our team makes a formal recommendation to the referring clinician, who remains the primary hematologist directing the day-to-day hematologic care of the patient, regarding degree of suspicion for an HMMS, plan for further evaluation and/or genetic testing, and any immediate impact on usual care for the patient’s HM (eg, related HSC donor selection must await results of genetic testing). Other practices may find referral to genetic counselors, specialized clinicians, or academic centers more appropriate for their practice needs. Table 2 can be used as a screening tool to guide the genetic workup for HMMSs in any clinical setting.

During the HMMS evaluation, the patient denies a history of easy bleeding or blood count abnormalities, but recalls that her mother may have had a low platelet count and required transfusions following childbirth. Her 42-year-old brother has frequent nosebleeds. Records confirm chronic thrombocytopenia in her mother and brother (platelet counts, 115 × 10⁹/L and 145 × 10⁹/L, respectively). FPD/AML is strongly suspected. Urgent single-site germ line testing of the RUNX1 mutation identified on somatic testing is recommended. A skin biopsy is performed at the site of her nadir BM biopsy for fibroblast culture. The primary hematologist is informed of the high suspicion for FPD/AML and recommended to avoid use of family donors unless a familial mutation is confirmed and the donor does not carry it.

The prevalence of HMMSs in most patient populations is unknown but is the subject of ongoing research. In small case series of children or young adults with MDS/AL or AA or in patients with HM tested for a suspicious personal or family history, the yield of germ line testing via gene panels ranges from 11% to 24%.^24,57,58  These yields approach those of solid tumors, such as early-onset breast cancer,⁵⁹  and justify genetic testing.

At present, we recommend clinical germ line genetic testing in: (1) families with 2 or more cases of MDS/AL; (2) families with MDS/AL and unexplained cytopenias/AA; and (3) individuals or families clustering MDS/AL with organ-system manifestations fitting a HMMS (Figure 1; Table 1). We routinely perform germ line testing for any individual whose tumor possesses mutations in genes associated with HMMSs (Table 1). This testing is performed on a clinical basis whenever possible. Germ line analysis is also imperative for: (1) biallelic CEBPA, as 7% to 11% of these individuals possess germ line CEBPA mutations^55,56 ; (2) a deleterious GATA2 mutation, especially in children/adolescents with MDS, as germ line GATA2 mutations are present in 7% of these cases overall and up to 72% of patients with monosomy 7 (many of these will be de novo germ line mutations with no family history or clinical features [Table 1] of germ line GATA2 deficiency⁶⁰ ); and (3) a deleterious RUNX1 mutation. Germ line RUNX1 mutations are associated with early-onset clonal hematopoiesis and cytopenias that may be erroneously treated as ITP, and germ line testing may therefore inform the care of the patient’s family.⁵⁸ 

Families clustering mixed myeloid and lymphoid malignancies or lymphoid malignancies alone are more challenging, as the genes responsible for the majority of these families are largely unknown, although a pathogenic germ line variant of the KDR gene is associated with familial Hodgkin lymphoma.⁶¹  We consider clinical testing for these families on a case-by-case basis based on specific HMMS patterns. For example, we do not routinely test families with familial chronic lymphocytic leukemia, but we do offer testing for families with AML segregating with T-cell acute lymphoblastic leukemia or follicular lymphoma, as these patterns may reflect HMMS (Table 1).⁶²  These recommendations will evolve as prevalence and yield of testing for HMMSs in different scenarios become available.

Given the phenotypic overlap of HMMSs, we often recommend panel-based NGS testing for the known HMMSs and/or IBMFSs, ensuring that all genes relevant for the patient scenario are included. We use panels from The University of Chicago or the University of Washington.^63,64  Single-gene and HMMS panels available at other laboratories can be found at www.genetests.org. Comprehensive techniques that detect point mutations and large deletions/duplications are essential, as these mutation types may cause HMMS. Once a familial mutation is identified in an individual, we perform site-specific testing for that particular mutation in other family members who seek testing. We may begin with site-specific testing if a deleterious HMMS mutation is identified on somatic tumor testing, but reflex to a larger panel if the patient scenario warrants. Standard germ line genetic testing clinical practice guidelines performed in other clinical scenarios should be followed, including pretest counseling about the reason for testing, testing alternatives, possible results, and how clinical management would change with or without testing.^65,66 

Genetic testing to identify germ line HMMS mutations requires careful tissue selection. In the setting of HM, the usual tissue source for germ line genetic testing in most other clinical scenarios, peripheral blood (PB), is an affected, tumor-containing tissue. Clonally skewed hematopoiesis further complicates PB analysis, as ∼1% of healthy patients under 50 years of age and 10% of healthy patients over 65 years of age will accumulate mutations in genes associated with MDS/AL, several of which cause HMMS if inherited in the germ line.^67,68  Thus, clinicians should avoid the use of PB, BM, or other tissues frequently contaminated with PB such as saliva, buccal cells, and DNA made directly from skin biopsies without culture. Our preferred source of germ line DNA from individuals with HM is DNA derived from cultured skin fibroblasts, usually obtained from a 3-mm skin-punch biopsy or by removing a skin ellipse at the site of a BM biopsy. The major disadvantage of utilizing cultured skin fibroblasts is the 3 to 6 weeks required to culture a sufficient number of cells for genetic testing.

Disclosure of clinical results in which a germ line deleterious mutation has been identified is best performed in person with a physician and/or genetic counselor familiar with HMMSs. These discussions are facilitated greatly by pretest counseling. Occasionally, individuals cannot return to clinic, and telephone/video conferencing is used as is done in other hereditary cancer genetics disclosure scenarios without adverse effects.^69,70  We also provide a “Family Letter” written in lay language summarizing our HMMS risk assessment, genetic testing results, recommendations for screening or follow-up care, and potential risk to and/or need for testing of additional family members. This letter is written for distribution to at-risk family members and the patient’s primary care and other physicians.

A 42-year-old man is diagnosed with chronic myelomonocytic leukemia-2 with isolated isochromosome 17q. An allogeneic hematopoietic stem cell transplant (HSCT) is recommended in first remission. The patient’s 3 siblings are queried as potential HSC donors, and 1 is an HLA-identical match. The family history reveals that their father died of AML at 53 years of age. How should recipient and donor evaluations proceed?

Waiting up to 12 weeks for a skin fibroblast culture and genetic testing results is not appropriate in urgent clinical scenarios like case 2. For urgent scenarios only, we use buccal swabs, saliva, or DNA made directly from a skin biopsy without culture, but clearly inform the testing laboratory and patient that any findings will need confirmation in their concurrently growing skin fibroblasts before final interpretation.

For time-critical HSCT decisions, our HMMS genetics team performs simultaneous evaluations of the recipient and related donor(s). These paired evaluations provide objective data, including the donor’s blood counts and physical examination, that may result in a clinical HMMS diagnosis. We may then advise directed genetic testing of 1 or more gene(s) by Sanger sequencing, which may have a shorter turnaround time compared with panel/array testing. At the same time, the transplant team performs an expedited matched unrelated donor search. We recommend an unrelated donor HSCT if suspicion for an HMMS is high but a specific germ line mutation cannot be identified in a family. If no HLA-matched unrelated donors are located, a careful discussion of the potential risks and benefits in that family’s unique scenario are revisited with both donor and recipient. Rarely, we have convened a team of ethicists, transplant physicians, hematologists, and geneticists to develop a consensus donor recommendation for a patient.

HMMS-focused evaluations of both the recipient and his HLA-matched sibling are urgently performed. The recipient has chronic cutaneous warts on the hands and feet and lymphedema in the right lower extremity of unclear etiology. The 35-year-old sibling is healthy, but his complete blood count (CBC) shows mild anemia and leukopenia. A BM biopsy of the sibling/potential donor reveals newly diagnosed MDS with monosomy 7. GATA2 deficiency syndrome is clinically suspected. Expedited panel-based genetic testing is sent from a skin-punch biopsy from the recipient with an additional biopsy sent for fibroblast culture. A germ line GATA2 mutation is confirmed. Unrelated donor HSCT is recommended for the proband and his sibling as no appropriate related donors exist. What are the unique care needs for this family?

Due to the recent description of these syndromes and the limited number of patients prospectively followed to date, evidence-based clinical surveillance and management recommendations for mutation carriers are not yet available but are the subject of ongoing research efforts.³⁸  Thus, current recommendations are expert opinion-based and modeled after clinical guidelines developed for IBMFSs and other syndromes featuring HM, such as FA and Li-Fraumeni syndrome.^{3,32,38,71,72}  The HMMS features of incomplete penetrance, variable phenotypic presentation, and anticipation all complicate development of clinical management recommendations even within a single syndrome.

There are unique considerations involved in the care of individuals with an HM who carry a germ line HMMS gene mutation. First, referral to a multidisciplinary team that includes a physician who is well-versed in HMMS should be considered. This referral facilitates assessment of all potential HMMS-specific organ-system manifestations that may impact the patient’s HM treatment (eg, immunodeficiency in GATA2 deficiency) and expedite referral to appropriate subspecialists. This team may also have knowledge of HMMS-specific treatment options such as decreased efficacy of immunosuppression in AA in patients with telomere syndromes or a potential increased response to lenalidomide in patients with MDS/AML and a DDX41 mutation.¹³  Furthermore, this team will facilitate genetic testing and/or monitoring of at-risk family members.

For patients with a deleterious mutation in an HMMS-associated gene and an active HM, we advocate performing an allogeneic HSCT, regardless of prognostic markers, using donors who lack the familial mutation in order to eradicate not only the MDS/AL but the HM-predisposed BM as well. This approach is not universal, as certain scenarios warrant induction/consolidation treatment with allogeneic HSCT at relapse/diagnosis of second primary leukemias. For example, patients with germ line CEBPA mutations may warrant initial treatment with only chemotherapy given the long remissions these patients experience.⁷ 

HSCT timing, preparative regimen, peritransplant care, and donor selection require special consideration. Preparative regimen selection is critical for some HMMSs, specifically the telomere syndromes, as these individuals may experience excess toxicity with agents such as busulfan or an increased likelihood of graft failure.^73-75  Differential outcomes with particular preparative regimens are not known in the other HMMSs at this time. Optimal peritransplant care includes a thorough evaluation for HMMS-specific organ manifestations in order to address presymptomatic organ dysfunction. In GATA2 deficiency, for example, antimicrobial prophylaxis is recommended against atypical mycobacteria.⁷⁶ 

Evaluation does not identify any additional GATA2 deficiency syndrome manifestations. Atypical mycobacterial prophylaxis is incorporated into the peritransplant care plan. Genetic counseling and testing are offered to the parents and siblings. The 40-year-old sister is found to carry the familial mutation. Her baseline clinical evaluation and CBC are normal. How should she be followed?

Surveillance recommendations include uniform recommendations for all mutation carriers, regardless of the specific gene involved, as well as recommendations unique to specific HMMSs (Table 3^{3,10,11,13,14,17-20,28,32,38,39,71-83} ). These recommendations may be adjusted based on an individual family’s presentation.

The age at which a baseline hematopoietic evaluation should be performed is based on the specific syndrome and family presentation. For example, an individual with a germ line DDX41 mutation and 3 relatives with MDS/AL with earliest case at 60 years of age should start surveillance in their 40s, whereas even children should be monitored in syndromes such as thrombocytopenia 5 that feature lifelong thrombocytopenia and platelet dysfunction. The initial baseline evaluation should include a CBC with differential, HLA typing, and consideration of a BM biopsy with cytogenetic analysis. Individuals with HMMSs featuring specific organ-system dysfunction should be monitored and treated for signs or symptoms of these conditions. All asymptomatic individuals with a normal baseline evaluation should have routine CBCs every 6 to 12 months. A repeat BM with cytogenetic analysis is essential if an individual develops CBC abnormalities. If this BM remains normal or similar to the patient’s baseline, a repeat CBC should be performed monthly and a repeat BM should be considered in 3 to 4 months, as recommended for IBMFSs featuring AA/MDS/AL.^3,23,32,72  The diagnosis of low-grade MDS without an identifiable cytogenetic abnormality is especially difficult in the setting of a germ line HMMS mutation. First, the mutation itself may cause subtle dyspoiesis. In addition, up to 81% of patients with germ line mutations in RUNX1 and GATA2, the 2 HMMSs examined to date, will develop clonal hematopoiesis by 50 years of age, further complicating the interpretation of acquired mutations in the PB or BM of these patients.⁵⁸  It is not yet clear which of these mutations signals impending malignancy development. At present, new clonal hematopoiesis in a patient should trigger closer surveillance and a more extensive workup. Genotyping of the pathogenic allele in matched related donors should be considered at diagnosis to avoid delays associated with genetic testing at the time of any future MDS/AL diagnoses. The prophylactic use of allogeneic HSCT in these individuals has been anecdotal to date and remains controversial in the field.⁸⁴  In some cases, an HSCT may be indicated for severe HMMS manifestations other than MDS/AL, such as AA in telomere syndromes, repeated severe infections in GATA2 deficiency syndromes, or the development of clonal hematopoiesis.⁷⁶ 

A substantial portion of families suspected of having an HMMS will fail to have a positive molecular diagnosis after testing for the currently known HMMS is complete. How should one care for families where the history is consistent with an HMMS but the molecular lesion remains undefined? If the personal or family history is undeniable (ie, a patient with pathologically confirmed AML in 4 first-degree family members, but a negative workup for all currently known gene mutations; or a patient with lymphedema, mycobacterial infection, and early-onset chronic myelomonocytic leukemia whose testing is negative for a GATA2 mutation), we provide a clinical diagnosis of the respective HMMS and provide care appropriate for that HMMS. If the family history is not clear, it is crucial to take into account the patient’s options and act in his/her best interests. We attempt to enroll patients suspected of having an HMMS, but who test negative for known pathogenic variants, on research protocols designed to both prospectively follow the patients as well as to facilitate new syndrome discovery (Figure 2).

Much remains to be learned in the field of HMMSs. We urge international centers to take family pedigrees and collect both germ line and malignant tissues from every patient using institutional review board–approved research protocols.⁸⁵  Participation should be offered to affected and unaffected family members to facilitate discovery, develop penetrance estimates, and populate long-term follow-up studies. Questions actively being pursued include: identification of novel inherited HM alleles, the prevalence of HMMSs in adult populations, the lifetime risks for specific HM and/or syndromic health problems, and the molecular mechanisms of disease in HM (Figure 3)^{6,8,9,17-19,34,35,80,86-89}  and the implications of these processes for the development of novel therapeutics and long-term patient care.

The field of HMMSs has expanded rapidly with the dissemination of more affordable NGS techniques and increased family history collection in adult hematology clinics. Early estimates suggest the proportion of unselected HM patients that may have a hereditary component approaches rates seen in other tumor types, such as high-risk breast cancer. Thus, there is a growing need for physicians, genetic counselors, and nurses who are well-versed in the diagnosis and management of individuals with HMMSs. Much remains to be learned about HMMSs, but we are hopeful that continued progress will be made and will eventually produce methods of prevention similar to the progress made in hereditary breast and ovarian cancers.

The authors thank their patients and families for their inspiration and participation in the research that has helped advance the field of inherited hematopoietic malignancies.

Contribution: M.W.D., S.F., J.E.C., and L.A.G. cowrote the paper and assisted with construction of tables and figures; and A.H.W. and M.F.J. assisted with editing of the paper and assisted with construction of tables and figures.

Conflict-of-interest disclosure: J.E.C. and L.A.G. receive royalties from their coauthored article on inherited hematopoietic malignancies in UpToDate. The remaining authors declare no competing financial interests.

The current affiliation for S.F. is Klinik für Innere Medizin III, Abteilung Hämatologie und Onkologie, Universitätsklinikum Ulm, Ulm, Germany.

A complete list of the members of The University of Chicago Hematopoietic Malignancies Cancer Risk Team who contributed to this article appears in “Appendix.”

Correspondence: Jane E. Churpek, The University of Chicago, 5841 S. Maryland Ave, MC 2115, Chicago, IL 60637; e-mail: jchurpek@medicine.bsd.uchicago.edu; and Lucy A. Godley, The University of Chicago, 5841 S. Maryland Ave, MC 2115, Chicago, IL 60637; e-mail: lgodley@medicine.bsd.uchicago.edu.

Members of The University of Chicago Hematopoietic Malignancies Cancer Risk Team who contributed to this article include: Michael W. Drazer, Simone Feurstein, Allison H. West, Matthew F. Jones, Jane E. Churpek, and Lucy A. Godley.