J Genet Counsel (2014) 23:910–921 DOI 10.1007/s10897-014-9754-z

REVIEW PAPER

Genetic Counseling for Fanconi Anemia: Crosslinking Disciplines Heather A. Zierhut & Rebecca Tryon & Erica M. Sanborn

Received: 10 March 2014 / Accepted: 31 July 2014 / Published online: 20 September 2014 # National Society of Genetic Counselors, Inc. 2014

Abstract Fanconi anemia (FA) is the most common of the inherited bone marrow failure syndromes with an incidence of approximately 1/100,000 to 1/200,000 live births. FA is a genetically complex and phenotypically heterogeneous condition involving birth defects, bone marrow failure, and cancer predisposition. This rare disease became well known in the genetic counseling community in 2002, when it was identified that biallelic mutations in BRCA2 can cause FA. Knowledge gained from the growing association between FA and breast cancer pathways has brought even more light to the complex genetic issues that arise when counseling families affected by this disease. Genetic counseling issues surrounding a diagnosis of FA affect many different disciplines. This review will serve as a way to cross-link the various topics important to genetic counselors that arise throughout the life of a patient with FA. Issues covered will include: an overview of FA, phenotypic presentation, management and treatment, the genetics and inheritance of FA, cytogenetic and molecular testing options, and the risks to family members of an individual with FA.

Keywords Genetic counseling . Genetic counselor . Fanconi anemia . Bone marrow transplantation . Bone marrow failure . DNA instability . Genetic testing . Chromosome breakage H. A. Zierhut (*) : R. Tryon Bone Marrow Transplantation Program, University of Minnesota Medical Center Fairview, Minneapolis, MN 55455, USA e-mail: [email protected] H. A. Zierhut Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA E. M. Sanborn Laboratory of Genome Maintenance, The Rockefeller University, New York, NY 10065, USA

Introduction Fanconi anemia (FA) is a complex, heterogeneous genetic condition and is the most common inherited form of aplastic anemia, affecting 1/100,000 to 1/200,000 live births (Rosenberg, Tamary, and Alter 2011; Swift 1971). The carrier frequency is estimated to be 1/181, with a higher rate in some ethnic backgrounds (Rosenberg et al. 2011). FA is characterized by a progressive pancytopenia (low red blood cells, low white blood cells, and low platelets), diverse congenital abnormalities and a predisposition to malignancy (Auerbach 2009). Both the genotypic and phenotypic heterogeneity of this condition presents unique challenges to the diagnosis and management of patients with FA. Genetic counselors have the opportunity to play a vital role in the management and care of patients and families affected by FA in a wide variety of specialties including cancer, prenatal, pediatric, reproductive and adult genetic counseling. Previously, the genetic counseling of individuals with FA was almost exclusive to pediatric genetic counselors; however, this landscape has expanded over time making a general knowledge of FA even more essential to genetic counselors in many subspecialties. The inclusion of numerous FA genes on cancer panels, the potential for preimplantation genetic diagnosis (PGD) or prenatal diagnostic testing in at-risk families, and the improvement of medical management leading to the emergence of an adult patient population with FA has greatly expanded the number of genetic counseling specialties that could be actively involved with these families. This resource is intended to assist genetic counselors and other health care professionals who play a critical role in providing optimal clinical care for patients and families affected by FA. Here we discuss the phenotypic spectrum of FA, the treatment and management of the

Genetic Counseling for Fanconi Anemia

condition, the genetic basis of the disease, the diagnostic process, and important counseling issues including testing family members, cancer risks in FA carriers, and reproductive options for these families.

911 Table 1 Clinical Manifestations of Fanconi Anemia System

% Of individuals with FA with given abnormalities

Common congenital abnormalities

Endocrine

79 %*

IUGR/Short stature Hypothyroidism Diabetes Growth hormone deficiency Decreased fertility

Skeletal

50 %*

Phenotypic Presentations of FA A general understanding of some of the common features can help genetic counselors identify individuals with FA. The majority of patients (66 %) are documented to have major congenital malformations (Giampietro et al. 1997). These can present in utero or in the perinatal period, but do not always lead to an immediate, accurate, or timely diagnosis with FA. The common clinical manifestations of FA are outlined in Table 1. As bone marrow failure is the most prominent and often initial presenting symptom in FA, genetic counselors working in hematology and bone marrow transplantation will inevitably interact with affected individuals and their families. Clinical signs of initial bone marrow dysfunction include: fatigue, frequent infection, and easy bruising. Decreases in red blood cells, white blood cells, and platelets can present with or without an antecedent illness or medication. Bone marrow failure commonly presents in the first decade of life and affects 90 % of individuals with FA by age 40 (Kutler et al. 2003). The differential diagnosis of any individual with thrombocytopenia (low platelets), pancytopenia, and/or aplastic anemia (mature blood cells cannot be generated due to damaged/empty bone marrow) should include FA (Oostra et al. 2012). For some individuals with FA, the first presentation of the disease is the development of a malignancy (Auerbach 2009). Individuals with FA are at a significantly higher risk to develop cancer than individuals in the general population. This risk is a 600 to 800-fold increase for acute myeloid leukemia (AML) and a 500-fold increase for solid tumors of the head and neck (Oostra et al. 2012; Shimamura and Alter 2010). Squamous cell carcinomas of the head, neck, and gynecologic regions are the most common and increases in other malignancies have been noted (Shimamura and Alter 2010). Counselors specializing in cancer should consider testing for FA when these cancers present at an earlier than expected age, have an atypical location, or when a patient has major toxicity to a normal treatment regimen (Oostra et al. 2012). It is critical that a proper diagnosis is made prior to receiving cancer treatment, as patients with FA can have toxic adverse reactions to chemotherapeutic agents and/or radiation, requiring careful consideration of the agent and dose to be used. Lastly, genetic counselors may identify an individual with FA through a detailed family history. Particular attention should be given to the common clinical manifestations of

Upper limbs (70 % of all skeletal defects)*

Thumb abnormalities Radial ray defects Hypoplastic thenar eminence Dysplastic ulna

Lower limbs

Toe syndactyly Abnormal toes Hip dislocation

Other Skeletal

Microcephaly Micrognathia Triangular face Sprengel deformity Klippel-Fiel Scoliosis Abnormal ribs

Integumentary

40 %#

Café-au-lait spots Hyperpigmentation Hypopigmentation

Renal

20 %#

Ectopic kidney Pelvic kidney Horseshoe kidney Hypoplastic/aplastic/ dysplastic kidney Hydronephrosis Hydroureter

Ears/hearing

11 %*

Deafness (usually conductive)

15 %*

Abnormal shape Atresia Abnormal middle ear

Gastrointestinal

7 %* 5 %#

Esophageal atresia Duodenal atresia Jejunal atresia Imperforate anus Tracheoesophageal fistula

Cardiopulmonary

6 %#

Various structural congenital heart defects

Eyes/vision

20 %#

Small eyes Close-set eyes Strabismus Epicanthal folds Cataracts Astigmatism

Gonads

25 %#

Males – 25%

Hypogenitalia Undescended testes Hypospadias Micropenis

2 %#

Females – 2%

Hypogenitalia Bicornuate uterus

#

Data from Shimamura and Alter (2010)

*Unpublished data cited in Alter (2008)

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FA (Table 1) and the associated cancers, with a special emphasis on squamous cell carcinoma of the head and neck, leukemia (AML), and cancers of the cervix, vulva, anus, breast, ovary, and prostate (Berliner et al. 2013; Shimamura and Alter 2010). In addition, a history of infertility can be significant. Information on the patient’s ethnic background can also provide clues to the best steps for initial testing.

Management/Treatment Treatment for individuals with FA is targeted at managing the individual symptoms as they arise. These treatments often include surgical corrections for congenital malformations and therapies to address common endocrine issues like hypothyroidism, diabetes mellitus and/or growth hormone deficiency (Rose et al. 2012). Individuals with FA are often followed with complete blood counts (CBC) to monitor the progression of bone marrow failure and with bone marrow aspirations to monitor for myelodysplastic syndrome (MDS). Currently, three possible treatments for the hematologic manifestations of FA are available. These include androgen therapies that can temporarily improve blood counts in 50 % of patients, transfusions of red blood cells or platelets to provide temporary hematopoietic support, and a hematopoietic stem cell transplant (HSCT), which is the only curative therapy of the hematologic symptoms of FA (Gluckman and Wagner 2008; Shimamura and Alter 2010). In the United States, there are three primary centers with FA comprehensive care and transplant programs: Cincinnati Children’s Hospital Medical Center, Memorial Sloan Kettering Cancer Center, and the University of Minnesota Children’s Hospital. Genetic counselors working with affected families might consider a referral to one of these specialized comprehensive care centers at the initial diagnosis of FA, ideally before bone marrow failure presents. These centers have the most experience in transplanting individuals with FA, giving them significant insight into when to initiate transplant, how to tailor the conditioning regimen, and how to address the common FA-related complications that can arise from transplant.

Genetics and Inheritance of FA Mutations in sixteen genes have been found to cause FA (Table 2) (Bogliolo et al. 2013). The FA proteins are known to function in the DNA repair of interstrand crosslinks (Taniguchi and D’Andrea 2006) (Fig. 1). Research to determine the specific functions of each of the genes associated with FA is ongoing and in many cases not well elucidated. Eight of the proteins form the FA core complex (Hodson and Walden 2012). The core complex has two known functions: localizing the complex to sites of DNA damage and the monoubiquitination of the FANCD2 protein (Hodson and

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Walden 2012). The FANCD2 and FANCI proteins form the ID complex, which then activates downstream homologous recombination proteins (Smogorzewska et al. 2007). Three of these downstream proteins called FANCD1 (BRCA2), FANCJ (BRIP1), and FANCN (PALB2) play an important role in cancer pathways (Bridge et al. 2005). Fifteen of the known FA subtypes are inherited in an autosomal recessive manner. Approximately 2 % of individuals with FA have mutations in the FANCB gene, which is inherited in an X-linked recessive pattern (Meetei et al. 2004; Shimamura and Alter 2010). Mutations in FANCA, FANCC, and FANCG collectively account for about 80 % of individuals with FA (Table 2). A small percentage of patients with FA who undergo genetic testing do not have mutations identified in any of the known FA genes, suggesting there are still unidentified genes operating in the FA pathway. Mutations in the FA genes can include missense, nonsense, and splice junction mutations as well as deletions, duplications, and inversions. To identify the wide range of possible mutations, a combination of genetic testing strategies may be necessary. Most mutations found in patients with FA are panethnic; however, founder mutations have been identified in certain ethnic groups (Table 3). De novo mutations can occur although the exact rates are not known. Other mechanisms of inheritance, including uniparental disomy, have been identified on a research basis and may affect recurrence risks in rare families. Of note, individuals with a single mutation in two distinct FA genes do not have Fanconi anemia. In most cases, predicting the clinical course of this genetically and clinically heterogeneous disease is limited by sparse and often conflicting genotype-phenotype correlations, yet in some cases, knowing the specific gene and mutations involved can have significant health implications. Some FA genes, like FANCD1 and FANCN, have clearly been shown to be associated with additional health risks that require further surveillance and management. These individuals are at risk for developing other solid tumors such as medulloblastoma, astrocytoma, and Wilms tumor (Alter et al. 2007; Hirsch et al. 2004; Offit et al. 2003; Reid et al. 2007). In addition, leukemia may develop at a much earlier age than is expected for individuals of other FA subtypes (Alter et al. 2007; Offit et al. 2003; Wagner et al. 2004). In other FA genes such as FANCA (Faivre et al. 2000; Castella et al. 2011), FANCC (Kutler et al. 2003; Yamashita et al. 1996), and FANCG (Faivre et al. 2000; Kutler et al. 2003), the genotype may be helpful for prognostic purposes (Neveling, Endt, Hoehn, and Schindler 2009) and may lead to increased monitoring or early intervention for individuals with a specific mutation.

Cytogenetic and Molecular Testing For FA The diagnosis and molecular characterization of FA is a multistep process (Fig. 2). Confirmation of the diagnosis at the

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Table 2 Information on genes known to cause FA Gene name

OMIM reference number

Chromosome location

Percent of FA cases

Percent of mutations due to deletions or duplications* (%)

FANCA FANCB FANCC FANCD1/BRCA2 FANCD2 FANCE FANCF FANCG FANCI

607139 300515 613899 600185 613984 613976 613897 602956 611360

16q24.3 Xp22.2 9q22.3 13q12.3 3p26 6p22–p21 11p15 9p13 15q26.1

65 % 2% 14 % 3% 3% 3% 2% 10 % 1%

61 % 48 % 24 % 43 % 13 % 4% 74 % 25 % 15 %

FANCJ/BRIP1 FANCL FANCM FANCN/PALB2 FANCO/RAD51C FANCP/SLX4 FANCQ/ERCC4

605882 608111 609644 610355 602774 613278 126380

17q22.2 2p16.1 14q21.2 16p12.2 17q25.1 16p13.3 19q13.32

2% 0.2 % 0.2 % 0.7 % 0.2 % 0.2 % Unknown

4% Unknown Unknown Unknown Unknown Unknown Unknown

*

Numbers calculated from data in the fanconi anemia mutation database (http://www.rockefeller.edu/fanconi/)

molecular level is important as the results from testing can impact medical management, prognosis, research eligibility, and reproductive risks. The process is often time-consuming, involving various tiers of testing. Here we propose an algorithm that can be used to assist providers in navigating this process; however, strategies may vary based on clinical presentation and availability of testing. If an individual has had transfusions, the genetic counselor should check with the clinical laboratory to determine how much time needs to pass before drawing and ordering the test in order to decrease the chance of inaccurate results. If an individual has had a HSCT, the blood collected after transplant will represent the DNA of the donor and therefore cannot be used.

Fig. 1 Simplified illustration of hypothesized fanconi anemia pathway

Chromosome Breakage Assay The chromosome breakage assay remains the most accurate method to diagnosis FA. In this test, metaphase chromosome spreads are analyzed before and after exposure to a crosslinking agent—typically diepoxybutane (DEB) or Mitomycin C (MMC) (Auerbach et al. 1981a, 1989; Auerbach and Wolman 1976). All chromosomal breaks, including the radial figures typically seen in individuals with FA, are quantified in multiple metaphase spreads and an average number of breaks per cell are reported (Auerbach et al. 1989). This test is initially performed on lymphocytes from peripheral blood but may be repeated in skin fibroblasts if the initial result is

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Table 3 Examples of FA founder mutations in ethnic populations Ethnicity

Gene

Mutation(s)

Carrier frequency

Reference

Ashkenazi Jewish

FANCC

c.456+4A>T (IVS4)

1/90

Whitney et al. 1993 and Verlander et al. 1995

FANCD1

c.6174delT

~1–2/100

Roa et al. 1996

Unknown

Castella et al. 2011

Brazilian

FANCA

c.3788_3790del

FANCG

c.1077–2A>G

Dutch/ Manitoba Mennonites French Acadian

FANCC

c.67delG (322delG)

Unknown

deVries et al. 2012

FANCG

c.1480+1G>C

Unknown

Auerbach et al. 2003

Israeli (Non AJ)

FANCA

Unknown

Tamary et al. 2000

Japanese

FANCA

c.2172dupG (Moroccan) c.4275delT (Moroccan) c.2574C>G (Indian) c.890-893del (Tunisian) c.2546delC c.3720_3724del c.456+4A>T

Unknown

Yagasaki et al. 2004

Unknown

Futaki et al. 2000

Unknown

Yagasaki et al. 2003

Unknown

Park et al. 2012

Unknown

Park et al. 2012

Unknown

Hartmann et al. 2010

~1/80

Rosendorff et al. 1987

FANCC FANCG Korean

FANCA FANCG

Saudi

FANCC

South African

FANCA

Auerbach et al. 2003

c.307+1G>C c.1066C>T c.2546delC c.3720_3724del c.307+1G>C c.1066C>T c.165+1G>T

Spanish Gypsy

FANCA

c.1007-?_3066+?del (Transvaal Province) c.1007-?_1626+?del (Transvaal Province) c.3398delA (Transvaal Province) c.637_643del (sub-Saharan Africa) c.295C>T

Turkish

FANCD2

c.1948-16 T>G

FANCG

negative or inconclusive and when FA is highly suspected (Gregory et al. 2001; Oostra et al. 2012). Following a positive chromosome breakage test, mutation analysis is the recommended next step in the genetic testing process (Oostra et al. 2012).

Complementation Testing Traditionally, complementation group testing was the first tier of testing following a positive chromosome breakage assay. Complementation testing assesses each FA protein individually to identify the dysfunctional protein in an individual with FA; however, this testing cannot provide information about the location or type of mutation (Chandra et al. 2005). If a dysfunctional protein is identified, single gene sequencing and, if necessary, deletion/duplication analysis of the corresponding gene is completed (Ameziane et al. 2008). This process can be both expensive and time-consuming

Tipping et al. 2001 Tipping et al. 2001 1/100

Morgan et.al. 2005

1/70

Callen et al. 2005

Unknown

Kalb et al. 2007

(Ameziane et al. 2012), and has been replaced by newer genetic testing technologies.

Targeted Mutation Analysis Targeted mutation analysis is helpful in testing patients with an ethnic background that has well-established founder mutation(s). Further, if the mutations are known for an individual affected with FA, genetic counselors can help facilitate targeted mutation analysis in other relatives for diagnostic testing, carrier testing, prenatal testing, and PGD.

Single Gene Sequencing Historically, single gene sequencing was used following the completion of complementation group testing. With the movement toward panel testing technologies, single gene

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915

Fig. 2 Proposed molecular testing algorithm. Different strategies may vary based on clinical presentation and availability of testing. *Duplication analysis available through select laboratories as part of panel testing

sequencing will likely be used mostly for testing partners of individuals with FA or carriers of an FA mutation.

et al. 2012). This testing can precede or follow next generation sequencing if the panel testing does not include this analysis.

Fanconi Anemia Panel Testing

Whole Exome/Genome Sequencing

Testing of all FA genes simultaneously can now be accomplished through panel testing using next generation sequencing technologies. It has many benefits over other testing methods, including reduced cost and turnaround times and, for some platforms, the ability to identify mutations in the deep intronic regions that are not typically detected in Sanger sequencing (Ameziane et al. 2012). It is recommended that families be offered panel testing for the known FA genes following a positive chromosome breakage study. If the panel does not include FANCD1/BRCA2 or if the phenotype is consistent with the more severe features typically seen in patients with mutations in FANCD1/BRCA2, testing should be ordered through a separate lab that can perform single-gene sequencing.

In rare instances, an individual carries a diagnosis of FA from chromosome breakage assays but no mutations are found through the genetic testing algorithm. In these instances, whole exome or whole genome sequencing may be warranted. Whole exome sequencing is beneficial in detecting mutations in a very large number of genes, but it cannot detect deep intronic mutations and not all regions of the exome will receive adequate coverage. Whole genome sequencing addresses this problem but both tests are costly, produce more variants of unknown significance, have longer turnaround times, and create more ethical dilemmas than more targeted approaches (Knies et al. 2012).

Comparative Genomic Hybridization and Multiplex Ligation-dependent Probe Amplification

As with all genetic testing, the current testing strategies have several important limitations. First, somatic lymphocyte mosaicism can lead to false negative chromosome breakage assays. An estimated 10-30 % of individuals with FA have lymphocyte mosaicism due to genetic reversion (Oostra et al. 2012). A mixed population of cells contains some cells that show typical breakage levels associated with FA while other cells show normal breakages. As chromosome breakage assay reports typically present the findings as an average number of

While next generation sequencing for FA significantly improves the testing process, it typically cannot detect all large deletions, duplications, and insertions that can account for up to one third of all FA mutations. Comparative genomic hybridization or multiplex ligation-dependent probe amplification may be an important part of the testing process (Knies

Limitations of Current Testing Technologies

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breaks per cell, mosaicism can lead to inconclusive or false negative results. To address this concern, it is beneficial to determine if the laboratory performing the chromosome breakage assay reports percentage of mosaicism. Experienced laboratories are recommended due to the difficulties in interpreting this assay. As with chromosome breakage assays, mutation analysis may not always supply a definitive result. It is possible for a proband to have only one mutation identified through sequencing technologies in one of the 15 autosomal recessive FA genes. Deletions and deep intronic mutations are the most common explanations for these findings (Ameziane et al. 2012). In these cases, dosage testing, further sequencing, RNA analysis, and/or SNP chips may be necessary to identify the second mutation. If exhaustive molecular analysis can only identify one mutation in the proband, it cannot be assumed that the causative gene has been identified without confirmatory complementation or functional analysis. As with any genetic testing, novel mutations or variants of uncertain significance can make determining the genetic nature of the disease challenging. By utilizing databases for common variants and pathogenicity predictive software, a prediction about the causality of the mutation can sometimes be formulated. The Fanconi Anemia Mutation Database was established as a cooperative effort to share information on previously identified mutations in the known FA genes. The database is a free resource that may be accessed at: www. rockefeller.edu/fanconi/mutate. When the significance of a variant remains unclear, follow up complementation testing or functional analysis should be done for confirmation. Functional analysis of more complex variants may require enrollment into a research study. Two examples of on-going research efforts for the FA community are the International Fanconi Anemia Registry (http://lab. rockefeller.edu/smogorzewska/ifar/) and the National Institute of Health Bone Marrow Failure Syndrome Study (http://www.marrowfailure.cancer.gov/).

Genetic Counseling Considerations of Current Molecular Technologies

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these tissue types. In some cases, genetic counselors may be called upon to address the sensitive issue of banking DNA for family use when the child or adult with FA has been given a poor prognosis before genetic testing has been performed. Additionally, banking samples for research purposes can be useful for individuals who do not have identifiable gene mutations via current testing methodologies so DNA can be preserved until additional FA genes are identified. Prenatal Testing for FA Prenatal testing for FA is ideally performed by site-specific mutation analysis (Ameziane et al. 2012). When site-specific mutation analysis is not possible, a chromosome breakage assay can be performed on chorionic villi or amniocytes (Auerbach et al. 1981). In addition to determining if the fetus is affected by FA, some individuals may also want to know the HLA-status of a pregnancy as a means of identifying a matched sibling donor. Prenatal HLA-typing is available and should be offered when appropriate. Preimplantation Genetic Diagnosis FA is the first condition for which in-vitro fertilization with preimplantation genetic diagnosis (IVF-PGD) was successfully used to test for both FA disease status and donor compatibility via HLA typing in 2000 (Grewal et al. 2004; Verlinsky, Rechitsky, Schoolcraft, Strom, and Kuliev 2001). Parents considering this procedure often pursue genetic counseling to learn about the steps involved and to discuss the complex emotional, ethical, and financial considerations associated with IVF-PGD. Counseling for these families should include a discussion of the chances of having a healthy, matched embryo. First, the theoretical chances of an individual having a matched sibling without FA includes a 3 in 4 chance that the embryo will not have FA and a 1 in 4 chance of being HLA identical; thus, the odds are 3 in 16 or 18.75 % for each embryo to not have FA and to be an HLA-match. In actuality, many couples will need multiple rounds of IVF and PGD to achieve a successful pregnancy resulting in a live-born baby (Zierhut, MacMillan, Wagner, and Bartels 2013).

DNA Banking Genetic Counseling for Family Members Once a patient has undergone HSCT, DNA can no longer be extracted from blood. It is important to consider DNA banking for any patient who will undergo HSCT prior to completing molecular confirmation of their diagnosis. If banked DNA is not available, genetic testing may be performed after transplant but will need to be completed from DNA collected by buccal swabs or skin biopsy. Not all assays have proper quality controls to perform next generation sequencing on

Fanconi Anemia Risk Assessment Parents Once two mutations are identified in an individual with FA, carrier testing can be offered to unaffected family members. All parents of children with FA should be offered carrier

Genetic Counseling for Fanconi Anemia

testing. While rare, it is possible that a parent of a child with FA will not carry either of their child’s FA mutations, which significantly alters the recurrence risk in the family. Possible explanations for this include de novo mutations, germline mosaicism, uniparental disomy, and misattributed paternity. If an individual or couple is at increased risk to have a child with FA, a referral to a genetic counselor is recommended. A discussion of all of the reproductive options with associated risks, benefits, and limitations should be reviewed with couples including: natural pregnancy, adoption, birth control, prenatal testing, gamete donation, and various assisted reproductive technologies such as IVF-PGD.

Siblings Due to the wide clinical variability in FA, all full biological siblings of a child with FA should have a chromosome breakage assay to exclude a possible diagnosis of FA (Giampietro et al. 1993). If the chromosome breakage assay is negative, it greatly reduces the chance that the child has FA. If the sibling has a phenotype highly suggestive of FA, fibroblast testing or mutation analysis of known FA mutations may be indicated. Molecular testing in unaffected minors without a suggestive FA phenotype should be delayed until they have reached reproductive age (Ross, Ross, Saal, David, and Anderson 2013).

Children of Individuals with FA Any biological child of an individual with FA will be an obligate carrier for FA. The chance that an individual who has been diagnosed with FA will have a child with the same condition is based on the carrier status of their partner. Ideally, an individual with FA would receive genetic counseling to discuss reproductive options and testing options for their partner when they reach adulthood. It is important to note that reduced fertility has been documented in females and males with FA (Chen et al. 1996).

Cancer Risk Assessment Cancer Risks for Fanconi Anemia Carriers Most carriers of a mutation in an FA gene are not at increased risk of developing cancer; however, several specific genes or mutations do appear to confer an increased cancer risk in carriers (Berwick et al. 2007). Family members of individuals with FA found to have a mutation in one of these genes should be referred to a genetic counselor for appropriate risk information and management options.

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FANCD1(BRCA2) Carriers Family members of individuals with biallelic mutations in the BRCA2 gene may be at significantly increased risk of developing certain cancers. Most families with FA who have mutations in the BRCA2 gene will present with the typical pattern of hereditary breast and ovarian cancer as reviewed in the NSGC guideline (Berliner et al. 2013). Other families may carry a hypomorphic mutation in the BRCA2 gene that is associated with FA but may not confer the same cancer risk seen in typical BRCA2 families (Alter et al. 2007). It is important to assess both the mutation and family history when discussing cancer risks with these families, as they may not fit the typical BRCA2 cancer risks. Carriers of a BRCA2 mutation are at a significantly increased risk for breast, ovarian, and prostate cancer and emerging evidence is showing increased risk for other cancers such as melanoma and pancreatic cancer (Berliner et al. 2013). Individuals found to carry a BRCA2 mutation should be referred for proper cancer genetic counseling and be presented with options for screening and management strategies based on established guidelines (NCCN 2013). FANCN (PALB2) Carriers Although patients with FA from mutations in FANCN and FANCD1 have a similar phenotype, carriers of FANCN mutations appear to have a lower risk of cancer when compared to BRCA2 carriers. Monoallelic truncating mutations in FANCN are associated with a two to five-fold increased risk of developing breast cancer when compared to the general population (Rahman et al. 2007; Tischkowitz et al. 2012). Erkko et al. found a cumulative risk of 40 % for developing breast cancer by age 70 in carriers of the Finnish founder mutation c.1592delT (Erkko et al. 2008). FANCN truncating mutations have also been reported in familial pancreatic cancer although estimates of the exact pancreatic cancer risks and screening recommendations for FANCN carriers have not been established (Jones et al. 2009; Slater et al. 2010). FANCN mutations have also been reported in male breast cancer (Ding et al. 2011). FANCN carriers are encouraged to discuss these cancer risks with their health care providers in order to design a screening plan which may entail more frequent clinical breast exams, mammograms or breast MRI examinations. No specific recommendations have been published on screening for FANCN carriers to our knowledge. FANCJ (BRIP1) Carriers Carrier risk in FANCJ individuals was first investigated in a group of patients with hereditary breast cancer who did not have mutations in the BRCA1 or BRCA2 genes. It was determined that truncating FANCJ mutations confer a relative risk

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of 2.0; however, the risk varied depending on the exact mutation, as some missense variants appear to confer a risk for breast cancer while others do not (Seal et al. 2006). Carriers of mutations known to confer an increased risk of breast cancer should be aware of this increased risk and seek medical advice to develop a screening plan. In addition, two Icelandic mutations (OR=8.1, 95%CI 4.7– 14.0, OR=25, 95 % CI 1.8–340, respectively) (Rafnar et al. 2011) and one Spanish frameshift mutation in FANCJ show a significantly increased risk of ovarian cancer. The Spanish mutation was also shown to confer an increased risk of breast cancer (OR=12, 95 % CI=1.9–70). One study has further indicated that truncating mutations in FANCJ are associated with a moderate increase in the risk of developing prostate cancer (OR=2.4, 95 % CI=0.25–23.4) (Kote-Jarai et al. 2009). FANCC Carriers The FANCC gene may confer an increased risk of breast cancer for mutation carriers. Berwick et al. showed that grandmothers that carried a FANCC mutation were 2.5 times more likely to develop breast cancer than non-carriers (Berwick et al. 2007). The molecular basis of this increased risk is not well understood and thus this finding must be further investigated. Carriers should be informed of this potentially increased risk and may consider discussing this finding with their health care providers; however, evidence for a specific association between breast cancer is not yet substantive (Ellis and Offit 2012). FANCO (RAD51C) Carriers A case report has shown a Fanconi-like syndrome presenting with biallelic mutations in RAD51C (Vaz et al. 2010). Carriers of deleterious mutations in RAD51C have been noted in cases of familial breast and ovarian cancer (Coulet et al. 2013; Osorio et al. 2012).

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has not been widely studied to date and no recommendations are currently available.

Summary FA is a unique, complex disease that spans many genetic counseling disciplines. Genetic counselors can play a vital role in the initial identification of FA and the evolving genetic testing algorithms that lead to an accurate and timely diagnosis. Genetic counselors can also provide an understanding of the caveats to the testing process to ensure that a diagnosis is appropriately verified and that individuals are referred for proper treatment and medical management. Additionally, genetic counselors will be critical to the interpretation process for genetic test results and to the explanation of important genetic testing considerations for family members. As with many genetic conditions, the impact on the family is substantial and can include significant reproductive risks and cancer predispositions. Genetic counselors must consider the many factors outlined in this review when counseling individuals with FA and their families. We believe cross-linking genetic counselor skills and disciplines will provide the best care for individuals with FA across their lifespan. Acknowledgments The authors would like to thank Jennifer Kennedy and Alicia Scocchia for their thoughtful review and comments on the manuscript. In addition, we would like to express our appreciation to the individuals with FA who have shared their stories through clinical care and research participation. We hope that this work will in some way make a difference in the care of families with FA. Erica Sanborn is supported by the Rockefeller University and by the Doris Duke Charitable Foundation Clinical Scientist Development Award to Agata Smogorzewska. Conflict of Interest The authors declare they have no conflict of interest. Animal and Human Studies No animal or human studies were carried out by the authors for this article.

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