Fanconi Anemia
Summary
Clinical characteristics.
Fanconi anemia (FA) is characterized by physical abnormalities, bone marrow failure, and increased risk for malignancy. Physical abnormalities, present in approximately 75% of affected individuals, include one or more of the following: short stature, abnormal skin pigmentation, skeletal malformations of the upper and lower limbs, microcephaly, and ophthalmic and genitourinary tract anomalies. Progressive bone marrow failure with pancytopenia typically presents in the first decade, often initially with thrombocytopenia or leukopenia. The incidence of acute myeloid leukemia is 13% by age 50 years. Solid tumors – particularly of the head and neck, skin, gastrointestinal tract, and genitourinary tract – are more common in individuals with FA.
Diagnosis/testing.
The diagnosis of FA is established in a proband with increased chromosome breakage and radial forms on cytogenetic testing of lymphocytes with diepoxybutane (DEB) and mitomycin C (MMC). The diagnosis is confirmed by identification of one of the following:
- Biallelic pathogenic variants in one of the 19 genes known to cause autosomal recessive FA
- A heterozygous pathogenic variant in RAD51, known to cause autosomal dominant FA
- A hemizygous pathogenic variant in FANCB, known to cause X-linked FA
Management.
Treatment of manifestations: Administration of oral androgens (e.g., oxymetholone) improves blood counts (red cell and platelets) in approximately 50% of individuals with FA; administration of G-CSF improves the neutrophil count in some; hematopoietic stem cell transplantation (HSCT) is the only curative therapy for the hematologic manifestations of FA, but the high risk for solid tumors remains and may even be increased in those undergoing HSCT. All these treatments have potential significant toxicity. Early detection and surgical removal remains the mainstay of therapy for solid tumors.
Prevention of primary manifestations: Human papilloma virus (HPV) vaccination to reduce the risk of gynecologic cancer in females, and possibly reduce the risk of oral cancer in all individuals.
Prevention of secondary complications: T-cell depletion of the donor graft to minimize the risk of graft vs host disease; conditioning regimen without radiation prior to HSCT to reduce the risk of subsequent solid tumors.
Surveillance: Annual evaluation with a multidisciplinary team including an endocrinologist; monitoring for evidence of bone marrow failure (regular blood counts; at least annual bone marrow aspirate/biopsy to evaluate morphology, cellularity, and cytogenetics); for those receiving androgen therapy, monitoring liver function tests and regular ultrasound examination of the liver; monitoring for solid tumors (oropharyngeal and gynecologic examinations).
Agents/circumstances to avoid: Transfusions of red cells or platelets for persons who are candidates for HSCT; family members as blood donors if HSCT is being considered; blood products that are not filtered (leukodepleted) or irradiated; toxic agents that have been implicated in tumorigenesis; unsafe sex practices, which increase the risk of HPV-associated malignancy; radiographic studies solely for the purpose of surveillance (i.e., in the absence of clinical indications).
Evaluation of relatives at risk: DEB/MMC testing or molecular genetic testing (if the family-specific pathogenic variants are known) of all sibs of a proband for early diagnosis, treatment, and monitoring for physical abnormalities, bone marrow failure, and related cancers.
Genetic counseling.
Fanconi anemia (FA) can be inherited in an autosomal recessive manner, an autosomal dominant manner (RAD51-related FA), or an X-linked manner (FANCB-related FA).
Autosomal recessive FA: Each sib of an affected individual has a 25% chance of inheriting both pathogenic variants and being affected, a 50% chance of inheriting one pathogenic variant and being a carrier, and a 25% chance of inheriting both normal alleles and not being a carrier. Carriers (heterozygotes) for autosomal recessive FA are asymptomatic.
Autosomal dominant FA: Given that all affected individuals with RAD51-related FA reported to date have the disorder as a result of a de novo RAD51 pathogenic variant, the risk to other family members is presumed to be low.
X-linked FA: For carrier females the chance of transmitting the pathogenic variant in each pregnancy is 50%; males who inherit the pathogenic variant will be affected; females who inherit the pathogenic variant will be carriers and will usually not be affected.
Carrier testing for at-risk relatives (for autosomal recessive and X-linked FA) and prenatal and preimplantation genetic testing are possible if the pathogenic variant(s) in the family are known.
Diagnosis
Recommendations for diagnosis were agreed upon at a 2013 consensus conference (see Fanconi Anemia: Guidelines for Diagnosis and Management).
Suggestive Findings
Fanconi anemia (FA) should be suspected in individuals with the following clinical and laboratory features.
Physical features (in ~75% of affected persons)
- Prenatal and/or postnatal short stature
- Abnormal skin pigmentation (e.g., café au lait macules, hypopigmentation)
- Skeletal malformations (e.g., hypoplastic thumb, hypoplastic radius)
- Microcephaly
- Ophthalmic anomalies
- Genitourinary tract anomalies
Laboratory findings
- Macrocytosis
- Increased fetal hemoglobin (often precedes anemia)
- Cytopenia (especially thrombocytopenia, leukopenia and neutropenia)
Pathology findings
- Progressive bone marrow failure
- Adult-onset aplastic anemia
- Myelodysplastic syndrome (MDS)
- Acute myelogenous leukemia (AML)
- Early-onset solid tumors (e.g., squamous cell carcinomas of the head and neck, esophagus, and vulva; cervical cancer; and liver tumors)
- Inordinate toxicities from chemotherapy or radiation
Establishing the Diagnosis
The diagnosis of FA is established in a proband with the following findings:
- Increased chromosome breakage and radial forms on cytogenetic testing of lymphocytes with diepoxybutane (DEB) and mitomycin C (MMC)Note: (1) The background rate of chromosome breakage in control chromosomes is more variable with MMC; thus, some centers use DEB while other centers use both DEB and MMC. (2) If results of lymphocyte testing are normal or inconclusive and mosaicism is suspected, testing can be performed on an alternative cell type, such as skin fibroblasts. See Fanconi Anemia: Guidelines for Diagnosis and Management.
- Identification of biallelic pathogenic variants in one of the 18 genes known to cause autosomal recessive FA, or a heterozygous pathogenic variant in RAD51 known to cause autosomal dominant FA, or a hemizygous pathogenic variant in FANCB, known to cause X-linked FA (see Table 1)
Molecular testing approaches can include single-gene testing, use of a multigene panel, and more comprehensive genomic testing:
- Single-gene testing. Sequence analysis of FANCA can be performed first, followed by gene-targeted FANCA deletion/duplication analysis if only one or no pathogenic variant is found.
- A multigene panel that includes the genes in Table 1a and Table 1b and other genes of interest (see Differential Diagnosis) may be considered next if single-gene testing does not identify a FANCA pathogenic variant. Note: (1) The genes included in the panel and the diagnostic sensitivity of the testing used for each gene vary by laboratory and are likely to change over time. (2) Some multigene panels may include genes not associated with the condition discussed in this GeneReview; thus, clinicians need to determine which multigene panel provides the best opportunity to identify the genetic cause of the condition at the most reasonable cost while limiting identification of pathogenic variants in genes that do not explain the underlying phenotype. (3) Methods used in a panel may include sequence analysis, deletion/duplication analysis, and/or other non-sequencing-based tests.For an introduction to multigene panels click here. More detailed information for clinicians ordering genetic tests can be found here.
- More comprehensive genomic testing (when available) including exome sequencing and genome sequencing may be considered if serial single-gene testing (and/or use of a multigene panel) fails to confirm a diagnosis in an individual with features of Fanconi anemia. Such testing may provide or suggest a diagnosis not previously considered (e.g., mutation of a different gene or genes that results in a similar clinical presentation).For an introduction to comprehensive genomic testing click here. More detailed information for clinicians ordering genomic testing can be found here.
Table 1a.
Gene 1, 2 | Complementation Group 3 | % of FA Attributed to Pathogenic Variants in Gene 4 | Proportion of Pathogenic Variants 5 Detected by Method | |
---|---|---|---|---|
Sequence analysis 6 | Gene-targeted deletion/duplication analysis 7 | |||
BRCA2 | FA-D1 | ~3% | >90% | None reported |
BRIP1 | FA-J | ~2% | >90% | None reported |
FANCA | FA-A | 60%-70% | ~60% | >20 deletion/duplication variants reported; see HGMD |
FANCB | FA-B | ~2% | Unknown | Deletion/duplication variants reported; see HGMD |
FANCC | FA-C | ~14% | Unknown | Several deletion/duplication variants reported; see HGMD |
FANCD2 | FA-D2 | ~3% | Unknown | Multiple deletion/duplication variants reported; see HGMD |
FANCE | FA-E | ~3% | >90% | None reported |
FANCF | FA-F | ~2% | Unknown | Deletion/duplication variants reported; see HGMD |
FANCG | FA-G | ~10% | >90% | None reported |
FANCI | FA-I | ~1% | Unknown | Deletion/duplication variant reported; see HGMD |
Pathogenic variants of any one of the genes included in this table account for >1% of FA
- 1.
Genes are listed in alphabetic order.
- 2.
See Table A. Genes and Databases for chromosome locus and protein.
- 3.
Prior to identification of the genes, complementation groups were defined based on somatic cell-based methods. While complementation analysis testing has been supplanted by multigene panels; this terminology continues to be used in some contexts.
- 4.
Shimamura & Alter [2010]
- 5.
See Molecular Genetics for information on pathogenic variants detected.
- 6.
Sequence analysis detects variants that are benign, likely benign, of uncertain significance, likely pathogenic, or pathogenic. Variants may include small intragenic deletions/insertions and missense, nonsense, and splice site variants; typically, exon or whole-gene deletions/duplications are not detected. For issues to consider in interpretation of sequence analysis results, click here.
- 7.
Gene-targeted deletion/duplication analysis detects intragenic deletions or duplications. Methods used may include quantitative PCR, long-range PCR, multiplex ligation-dependent probe amplification (MLPA), and a gene-targeted microarray designed to detect single-exon deletions or duplications.
Table 1b.
Gene 1, 2, 3 | Complementation Group 4 | Comment |
---|---|---|
ERCC4 | FA-Q | 2 persons w/FA & biallelic ERCC4 pathogenic variants reported [Bogliolo et al 2013]; functional studies of ERCC4 missense variants reported by Osorio et al [2013] |
FANCL | FA-L | 13 FANCL pathogenic variants reported [Chandrasekharappa et al 2013, Nicchia et al 2015, Vetro et al 2015] |
FANCM | FA-M | Assignment of a formal complementation group for persons w/FANCM pathogenic variants still controversial as only 1 reference family/cell line has been identified & that cell line has been determined to have biallelic pathogenic variants in both FANCA & FANCM. Of note, under experimental conditions specific knockdown of FANCM alone results in an FA phenotype [Singh et al 2009]. |
MAD2L2 | FA-V | 1 person w/homozygous pathogenic variants reported [Bluteau et al 2016] |
PALB2 | FA-N | 14 PALB2 pathogenic variants reported incl a deletion of exons 1-10 [Reid et al 2007, Xia et al 2007, Byrd et al 2016] |
RAD51 | FA-R | 2 persons w/features of FA & a de novo RAD51 pathogenic variant reported [Ameziane et al 2015, Wang et al 2015] |
RAD51C | FA-O | Assignment of a formal complementation group for persons w/RAD51C pathogenic variants still controversial as only 1 reference consanguineous family identified [Vaz et al 2010] |
RFWD3 | FA-W | 1 person w/features of FA & compound heterozygous pathogenic variants in RFWD3 reported [Knies et al 2017] |
SLX4 | FA-P | Assignment of a formal complementation group for persons w/SLX4 pathogenic variants still controversial as only a handful of reference families have been identified & SLX4 biology falls outside previously characterized FA proteins [Kim et al 2011, Stoepker et al 2011] |
UBE2T | FA-T | 1 person w/biallelic UBE2T pathogenic variants incl a large paternal deletion & a maternal duplication reported [Rickman et al 2015, Virts et al 2015] |
XRCC2 | FA-U | 1 person w/homozygous pathogenic variants reported [Park et al 2016] |
Pathogenic variants of any one of the genes listed in this table are reported in only a few families (i.e., <1% of FA)
- 1.
Genes are listed in alphabetic order.
- 2.
See Table A. Genes and Databases for chromosome locus and protein.
- 3.
Genes are not described in detail in Molecular Genetics but may be included here (pdf).
- 4.
Prior to identification of the genes, complementation groups were defined based on somatic cell-based methods this terminology continues to be used in some contexts.
Clinical Characteristics
Clinical Description
The primary clinical features of Fanconi anemia (FA) include physical features, progressive bone marrow failure manifest as pancytopenia, and cancer susceptibility; however, some individuals with FA have neither physical abnormalities nor bone marrow failure.
Physical features occur in approximately 75% of individuals with FA.
- Growth deficiency: prenatal and/or postnatal short stature, low birth weight
- Abnormal skin pigmentation (40%): generalized hyperpigmentation; café au lait macules, hypopigmentation
- Skeletal malformations of upper limbs, unilateral or bilateral (35%):
- Thumbs (35%): absent, hypoplastic, bifid, duplicated, triphalangeal, long, proximally placed
- Radii (7%): absent or hypoplastic (only with abnormal thumbs), absent or weak pulse
- Hands (5%): flat thenar eminence, absent first metacarpal, clinodactyly, polydactyly
- Ulnae (1%): dysplastic, short
- Skeletal malformations of lower limbs (5%)
- Syndactyly, abnormal toes, club feet
- Congenital hip dislocation
- Microcephaly (20%)
- Ophthalmic (20%): microphthalmia, cataracts, astigmatism, strabismus, epicanthal folds, hypotelorism, hypertelorism, ptosis
- Genitourinary tract anomalies:
- Renal (20%): horseshoe, ectopic, pelvic, hypoplastic, dysplastic, or absent kidney; hydronephrosis or hydroureter
- Males (25%). Hypospadias, micropenis, cryptorchidism, anorchia, hypo- or azoospermia, reduced fertility
- Females (2%). bicornuate or uterus malposition, small ovariesNote: Pregnancy is possible in females, whether or not they have undergone hematopoietic stem cell transplantation.
- Endocrine: hypothyroidism, glucose/insulin abnormalities
- Hearing loss, usually conductive secondary to middle ear bony anomalies; abnormal ear shape: dysplastic, narrow ear canal, abnormal pinna (10%)
- Congenital heart defect (6%): patent ductus arteriosus, atrial septal defect, ventricular septal defect, coarctation of the aorta, truncus arteriosus, situs inversus
- Gastrointestinal (5%): esophageal, duodenal, or jejunal atresia, imperforate anus, tracheoesophageal fistula, annular pancreas, malrotation
- Central nervous system (3%): small pituitary, pituitary stalk interruption syndrome, absent corpus callosum, cerebellar hypoplasia, hydrocephalus, dilated ventricles
- Other
- Facial features (2%): triangular, micrognathia, mid-face hypoplasia
- Spine anomalies (2%): spina bifida, scoliosis, hemivertebrae, rib anomalies, coccygeal aplasia
- Neck anomalies (1%): Sprengel deformity, Klippel-Feil anomaly, short or webbed neck, low hairline
Note: Percentages are calculated from 2,000 individuals reported in the literature from 1927 to 2009. Frequencies are approximate, since many reports did not mention physical descriptions.
Developmental delay and/or intellectual disability (10%)
Bone marrow failure. The age of onset is highly variable, even among sibs. An analysis of 754 individuals with pathogenic variants in FANCA, FANCC, and FANCG identified an average age of onset of 7.6 years. Rarely, bone marrow failure can present in infants and small children [Shimamura & Alter 2010]. The risk of developing any hematologic abnormality is 90% by age 40 years [Kutler et al 2003].
- Thrombocytopenia or leukopenia usually precede anemia. These are commonly associated with macrocytosis and elevated fetal hemoglobin.
- Pancytopenia generally worsens over time.
- Sweet syndrome (neutrophilic skin infiltration) was associated with progression of hematologic disease in six out of seven individuals with FA [Giulino et al 2011].
- The severity of bone marrow failure can be classified by the degree of cytopenia(s) (Table 3). Importantly, to meet these criteria for marrow failure, the cytopenias must be persistent and unexplained by other causes.
Table 2.
Mild | Moderate | Severe | |
---|---|---|---|
Absolute neutrophil count (ANC) | <1,500/mm3 | <1,000/mm3 | <500/mm3 |
Platelet count | 150,000-50,000/mm3 | <50,000/mm3 | <30,000/mm3 |
Hemoglobin (Hb) level | ≥8 g/dL | <8 g/dL | <8 g/dL |
Cancer susceptibility. The relative risk for acute myelogenous leukemia (AML) is increased approximately 500-fold [Rosenberg et al 2008, Alter et al 2010, Tamary et al 2010]. In a competing risk analysis of the combined cohorts, the cumulative incidence of AML was 13% by age 50 years, with most individuals diagnosed between ages 15 and 35 years.
An increased risk of developing myelodysplastic syndrome (MDS)/AML is associated with monosomy 7 and most 7q deletions. Clonal amplifications of chromosome 3q26-q29 were reported in association with an increased risk of progression to MDS/AML [Neitzel et al 2007, Mehta et al 2010].
Solid tumors may be the first manifestation of FA in individuals who have no birth defects and have not experienced bone marrow failure.
- Head and neck squamous cell carcinomas (HNSCCs) are the most common solid tumor in individuals with FA. The incidence is 500- to 700-fold higher than in the general population. The HNSCCs in FA show distinct differences compared to HNSCCs seen in the general population. HNSCCs:
- Occur at an earlier age (20-40 years) than in the general population;
- Are most commonly in the the oral cavity (e.g., tongue);
- Present at an advanced stage;
- Respond poorly to therapy.
- Individuals with FA are at increased risk for second primary cancers in the skin and genitourinary tract. The pattern of second primaries resembles that observed in HPV-associated HNSCC in the general population [Morris et al 2011].
- Individuals with FA receiving androgen treatment for bone marrow failure are also at increased risk for liver tumors.
Phenotype Correlations by Gene
BRCA2. Biallelic pathogenic variants in BRCA2 are associated with early-onset acute leukemia and solid tumors [Hirsch et al 2004, Wagner et al 2004, Myers et al 2012]. The cumulative probability of any malignancy was 97% by age six years, including AML, medulloblastoma, and Wilms tumor [Alter et al 2007].
FANCG. Pathogenic variants in FANCG may be associated with severe marrow failure and a higher incidence of leukemia compared to FANCC [Faivre et al 2000].
PALB2. Solid tumors (e.g., medulloblastoma, Wilms tumor) are associated with PALB2 pathogenic variants [Reid et al 2007].
Genotype-Phenotype Correlations
The clinical spectrum of FA remains heterogenous. There are no clearcut genotype-phenotype correlations [Neveling et al 2009]. In general, null variants lead to a more severe phenotype (e.g., congenital anomalies, early-onset bone marrow failure, and MDS/AML) than hypomorphic variants.
BRCA2. All persons with an IVS7 pathogenic variant in BRCA2 developed AML by age three years; those with other BRCA2 pathogenic variants who developed AML did so by age six years [Alter 2006].
FANCA. Individuals who are homozygous for null pathogenic variants in FANCA may have earlier onset of anemia and higher incidence of leukemia than individuals with pathogenic variants that permit production of an abnormal FANCA protein [Faivre et al 2000].
FANCC
- c.456+4A>T, p.Arg548Ter, and p.Leu554Pro are associated with earlier onset of hematologic abnormalities and more severe congenital anomalies than other pathogenic variants, such as del22G [Faivre et al 2005].
- p.Asp23IlefsTer23 and p.Gln13Ter are associated with a lower risk for congenital anomalies and later progression to bone marrow failure [Yamashita et al 1996, Gillio et al 1997].
- c.456+4A>T results in a milder phenotype in Japanese individuals than in Ashkenazi Jewish individuals [Futaki et al 2000].
Prevalence
Fanconi anemia (FA) is the most common genetic cause of aplastic anemia and one of the most common genetic causes of hematologic malignancy.
The ratio of males to females is 1.2:1 (p<0.001 vs expected 1.00).
Rosenberg et al [2011] showed higher carrier rates for FA than previously reported. Carrier frequency was 1:181 in North Americans and 1:93 in Israel. Specific populations have founder variants with increased carrier frequencies (<1:100), including Ashkenazi Jews (FANCC, BRCA2), northern Europeans (FANCC), Afrikaners (FANCA), sub-Saharan Blacks (FANCG), Spanish Gypsies (FANCA), and others.
Differential Diagnosis
Cells derived from individuals with other chromosome breakage syndromes, such as Bloom syndrome or ataxia-telangiectasia, may also exhibit high rates of spontaneous chromosome breakage; however, only FA cells exhibit increased chromosome breakage in response to diepoxybutane (DEB).
Nijmegen breakage syndrome (NBS), characterized by short stature, progressive microcephaly with loss of cognitive skills, premature ovarian failure in females, recurrent sinopulmonary infections, and an increased risk for cancer (particularly lymphoma), may also manifest increased chromosome breakage with mitomycin C (MMC) [Chrzanowska et al 2012]. Inheritance is autosomal recessive. NBS may be distinguished from FA by NBN molecular genetic testing, which identifies pathogenic variants in almost 100% of individuals with NBS.
Seckel syndrome (OMIM PS210600), characterized by growth retardation, microcephaly with intellectual disability, and a characteristic "bird-headed" facial appearance, may also show increased chromosome breakage with DNA cross-linking agents (MMC, DEB) [Andreassen et al 2004]. Some individuals with Seckel syndrome also develop pancytopenia and/or AML. Inheritance is autosomal recessive. Biallelic pathogenic variants in ATR, NIN, ATRIP, RBBP8, CEP152, CENPJ, and CEP63 are causative.
Other disorders including neurofibromatosis 1 (which could be considered because of café au lait macules), TAR syndrome (thrombocytopenia with absent radii), and VACTERL association (radial ray defects) (OMIM 192350) can be distinguished from FA by testing for chromosome breakage with DEB and MMC.
Management
Evaluations Following Initial Diagnosis
To establish the extent of disease and management requirements in an individual diagnosed with Fanconi anemia (FA), the following evaluations are recommended:
- Evaluation by a hematologist, to include complete blood count, fetal hemoglobin, full blood typing, blood chemistries (assessing liver, kidney, and iron status), and bone marrow aspirate for cell morphology, FISH and cytogenetics, as well as biopsy for cellularityNote: The bone marrow of individuals with FA can exhibit signs of dysplasia, such as nuclear/cytoplasmic dys-synchrony, hypo-lobulated megakaryocytes, and bi-nucleated erythroid cells. These features must be distinguished from true forms of MDS by a hematopathologist experienced in the evaluation of MDS in individuals with FA.
- HLA typing of the affected individual, sibs, and parents for consideration of hematopoietic stem cell transplantation
- Examination by an ophthalmologist
- Ultrasound examination of the kidneys and urinary tract
- Formal hearing evaluation
- Echocardiogram
- Referral to an endocrinologist
- Developmental assessment (particularly important for toddlers and school-age children)
- Referrals as indicated to an otolaryngologist, hand surgeon, gastroenterologist, gynecologist, and urologist
- Evaluation by a clinical geneticist and genetic counseling
Treatment of Manifestations
Recommendations for treatment were agreed upon at a 2014 consensus conference (full text).
Androgens improve (at least transiently) the red cell and platelet counts in approximately 50% of individuals. Androgen therapy can be considered when the hemoglobin drops below 8 g/dL or the platelet count falls below 30,000/mm3 ("severe" – see Table 2). Although only 10%-20% of individuals receiving continuous low-dose androgen therapy are long-term responders, this option can be particularly useful for individuals who do not have access to or are not ready for hematopoietic stem cell transplant (HSCT), or to individuals for whom of a suitable donor is not available.
- Oxymetholone, given orally at a starting dose of 2 mg/kg/day, may be increased up to 5 mg/kg/day.
- Doses may be slowly tapered to the minimal effective dose with careful monitoring of the blood counts.
- Other synthetic androgens used in FA include stanazolol in Asia, and oxandrolone and danazol in North America.
Side effects of androgen administration include virilization and liver toxicity such as elevated liver enzymes, cholestasis, peliosis hepatis (vascular lesion with multiple blood-filled cysts), and hepatic tumors. Individuals taking androgens should be monitored for liver tumors and undergo regular liver function tests (LFT) for abnormalities. Blood tests for LFTs should be performed every three to six months; liver ultrasound should be performed every six to 12 months. If no response is seen after three to four months, androgens should be discontinued [Scheckenbach et al 2012, Rose et al 2014].
Granulocyte colony-stimulating factor (G-CSF) improves the neutrophil count in some individuals. G-CSF dose should be titrated to the lowest possible dose and frequency to keep ANC above 1,000/mm3. Note: (1) A bone marrow aspirate and biopsy should be performed prior to the initiation of G-CSF and monitored every six months throughout treatment, given the theoretic risk of stimulating the growth of a leukemic clone. (2) G-CSF should be administered in consultation with an FA expert.
Hematopoietic stem cell transplantation (HSCT) is the only curative therapy for the hematologic manifestations, including aplastic anemia, myelodysplastic syndrome, and acute leukemia. Ideally, HSCT is performed prior to onset of MDS/AML and before multiple transfusions [MacMillan & Wagner 2010, Mehta et al 2010]. Individuals with FA are sensitive to chemotherapy and radiation, need special transplant regimens, and should be cared for and transplanted at centers with the most experience in HSCT in FA.
A multi-institutional study reported a one-year probability of overall survival of 80% in 45 individuals with FA transplanted for marrow failure and/or MDS, using alternative donors (including mismatched related and unrelated donors) and chemotherapy-only preparative regimen. Survival for individuals younger than age ten years transplanted for marrow failure was even better, at 91.3% (±5.9%) [Mehta et al 2017].
Fludarabine reduced the incidence of graft failure and allowed for removal of radiation from the preparative regimens in a matched sib donor setting [MacMillan et al 2015].
MDS/AML treatment remains challenging. Options include chemotherapy, HSCT with or without prior induction chemotherapy, and investigational trials. Chemotherapy should be undertaken in coordination with centers experienced with FA, as it can cause severe, prolonged, or irreversible myelosuppression. Plans for HSCT should be in place prior to starting chemotherapy. Published reports of chemotherapy regimens for AML in individuals with FA are sparse and limited by the unclear benefit to the overall outcome due to the lack of longitudinal follow up [Mehta et al 2007, Talbot et al 2014, Beier et al 2015].
Solid tumors. Prompt, aggressive workup for any symptoms suggestive of a malignancy is indicated. Early detection and surgical removal remains the mainstay of therapy. Treatment is challenging secondary to the increased toxicity associated with chemotherapy and radiation in FA. Data is limited on use of chemotherapy at standard doses or reduced doses and schedules in individuals with FA, and there are reports of severe or fatal toxicities and poor treatment outcomes [Masserot et al 2008, Hosoya et al 2010, Tan et al 2011, Spanier et al 2012]. Individuals diagnosed with a genital tract cancer should be referred to a gynecologic oncologist immediately, and care should be coordinated with FA experts.
Prevention of Primary Manifestations
Human papilloma virus (HPV) vaccination should be initiated at age nine years in order to reduce the risk of gynecologic cancer in females, and possibly reduce the risk of oral cancer in all individuals.
Prevention of Secondary Complications
Individuals with FA treated with HSCT who developed graft vs host disease (GVHD) had a 28% incidence of head and neck cancers in the ten years following treatment (vs 0% in those without GVHD); this finding points to the importance of minimizing the risk of GVHD [Guardiola et al 2004]. Increased risk for GVHD observed in earlier studies was reduced significantly by T-cell depletion of the donor graft [Chaudhury et al 2008, MacMillan et al 2015].
Individuals successfully treated with HSCT are at increased risk for solid tumors, in addition to the baseline increased risk [Rosenberg et al 2005]. Due to the known contribution of radiation to the long-term complication of secondary solid tumors most recent efforts have focused on using a conditioning regimen without radiation even in an unrelated donor setting. German, Brazilian, and US groups now report excellent outcomes with alternative donors with a "chemotherapy-only" preparative regimen in single-center studies. The study from Germany showed 88% survival and normal hematopoiesis at a median follow up of 30 months [Bonfim et al 2015, Chao et al 2015]. A prospective multi-institutional US study also showed similar excellent outcomes. One-year probabilities of overall and disease-free survival for the entire cohort, including patients with myeloid malignancy and those receiving mismatched related/haploidentical grafts, were 80% and 77.7% respectively at a median follow-up of 41 months. All young children (age <10 years) undergoing HSCT for marrow failure using low-dose busulfan-containing regimen survived [Mehta et al 2017].
Surveillance
See 2014 consensus guidelines [Frohnmayer et al 2014] (full text).
- Annual evaluation with a multidisciplinary team including an endocrinologist
- Regular blood counts, every three to four months while stable and more often as needed
- Bone marrow aspirate/biopsy at least annually to evaluate morphology, cellularity (from the biopsy), FISH, and cytogenetics (the latter two for emergence of a malignant clone). Individuals on GCSF need to have a bone marrow aspirate/biopsy every six months, if possible.
- In individuals who develop Sweet syndrome (neutrophilic skin infiltration), prompt investigation for hematologic disease progression including bone marrow evaluation
Notes: (1) Progressively changing blood counts without a potential cause (e.g., acute infection or suppression from medication) require immediate evaluation with a complete blood count and bone marrow examination with FISH and cytogenetics. (2) It is important to recognize that rising blood counts can be due to either the development of MDS/AML or, rarely, reversion of a germline mutation in a stem cell, which repopulates the marrow with normal cells (somatic stem cell mosaicism). These individuals may require immediate HSCT (for MDS/AML) or continued close monitoring with complete blood counts at least every one to two months and a bone marrow examination with cytogenetics every six months.
Individuals receiving androgen therapy
- Liver function tests every three to six months
- Liver ultrasound examination every six to 12 months for androgen-related changes, including tumors
Cancer surveillance
- Annual gynecologic assessment for genital lesions beginning at age 13. Thorough vulvo-vaginal examinations and Pap smear can begin when women become sexually active or by age 18 years, whichever is earlier. Suspicious genital tract lesions should be biopsied.
- Examination every six months for oral, head, and neck cancers beginning by age nine to ten years. Screening should be performed by a dentist, oral surgeon, or ENT familiar with FA. Nasolaryngoscopy starting at age ten years, or within the first year after HSCT. Individuals with difficulty or pain with swallowing should be evaluated for esophageal cancer.
- For individuals with a history of premalignant or malignant lesions: surveillance examinations every two to three months
- For individuals with biallelic pathogenic variants in BRCA2: screening for neuroblastomas, brain tumors, and kidney tumors every six months (see also Autosomal Recessive FA, Risk to Family Members)
Agents/Circumstances to Avoid
Blood transfusions. Blood products should be cytomegalovirus (CMV)-safe and irradiated. To reduce the chances of sensitization, family members must not act as blood donors. Once an individual requires transfusions, he/she should be referred for transplantation.
Toxic agents to avoid include smoking, second-hand smoke, and alcohol, which have been implicated in tumorigenesis.
Unsafe sex practices increase the risk for HPV-associated malignancy.
Radiographic studies for the purpose of surveillance should be minimized in the absence of clinical indications. However, baseline skeletal surveys may be considered, in order to document bony anomalies that may lead to problems with age, such as anomalies of the wrist, hip, and vertebrae.
Evaluation of Relatives at Risk
It is appropriate to evaluate all sibs of an affected individual in order to identify as early as possible those who would benefit from appropriate monitoring for physical abnormalities, bone marrow failure, and related cancers.
- DEB/MMC testing can be used to clarify the disease status of at-risk sibs.
- If the pathogenic variant(s) in the family are known, molecular genetic testing can be used to clarify the genetic status of at-risk sibs.
See Genetic Counseling for issues related to testing of at-risk relatives for genetic counseling purposes.
Pregnancy Management
Pregnancy is possible in females with FA, whether or not they have undergone hematopoietic stem cell transplantation [Dalle et al 2004, Nabhan et al 2010].
Pregnancy needs to be managed by a high-risk maternal fetal obstetrician along with a hematologist.
Therapies Under Investigation
Previous clinical trials failed to accomplish permanent gene correction of stem cells; current work is focusing on development of novel vector and delivery strategies [Tolar et al 2011]. The first FA lentiviral gene therapy trial led by the University of Washington/Fred Hutchinson Cancer Research Center is now open [Becker et al 2010]. Dr Juan Bueren has an open trial of a hematopoietic stem cell mobilization in Madrid, Spain and plans to have their FANCA gene therapy trial opened soon.
A Phase I study of the antioxidant quercetin in children with Fanconi anemia is currently underway at Cincinnati Children's Hospital Medical Center.
Search ClinicalTrials.gov in the US and EU Clinical Trials Register in Europe for access to information on clinical studies for a wide range of diseases and conditions.