What's Fanconi anemia?
Fanconi anemia is an inherited DNA-repair disorder: the FANC pathway proteins normally repair DNA interstrand crosslinks, so when they fail, cells accumulate damage (genomic instability). It is characterized by progressive bone marrow failure (pancytopenia), congenital anomalies, and a markedly increased risk of cancer, especially leukemia/myelodysplasia and squamous-cell cancers of the head and neck. It is caused by variants in any of more than 20 FANC genes; most cases are autosomal recessive (one form is X-linked). Diagnosis rests on a chromosome-breakage test using diepoxybutane or mitomycin C. This entry confirms FANCA, the most common gene, as the principal driver and leaves the rest of the pathway as unconfirmed scaffold. Note: Fanconi ANEMIA (this disorder) is unrelated to Fanconi SYNDROME, a renal proximal-tubule defect.
| Also indexed as | ORPHA:84, MONDO:0019391 |
|---|---|
| Features mapped | 18 |
| Treatments mapped | 3 |
| Published sources | 19 |
| Last reviewed | 2026-08-04 |
Signs and symptoms
Absent radius
Some children with Fanconi anemia are born with differences in the bones of the forearm and thumb, known as radial ray defects, which can include a missing or underdeveloped radius (one of the two forearm bones). These are among the typical congenital differences that can point toward the condition.
Absent thumb
Differences in the thumb and the bones of the forearm are characteristic of Fanconi anemia. In some children this includes a missing or malformed thumb, part of the thumb and radial bone anomalies that can be present from birth.
Short stature
Short stature and poor growth are common, part of the developmental picture of the syndrome.
Thrombocytopenia
As the bone marrow in Fanconi anemia gradually fails, the number of platelets (the cell fragments that help blood clot) can fall. A low platelet count is part of the wider drop in blood cells seen in the condition, and can show up as easy bruising or small pinpoint spots of bleeding in the skin.
Reticulocytopenia
Reticulocytes are very young red blood cells just released by the bone marrow, so their number shows how actively new red cells are being made. In Fanconi anemia this count can be low, reflecting that the failing bone marrow is not replacing red blood cells as it should.
Pancytopenia
The hematologic hallmark is progressive pancytopenia: falling counts of red cells, white cells, and platelets as the bone marrow fails, usually beginning in childhood.
Bruising susceptibility
As the marrow makes fewer platelets, people with Fanconi anemia bruise easily and may develop small pinpoint skin bleeds (petechiae), often before a formal diagnosis is made.
Anemia
In Fanconi anemia the bone marrow slowly loses its ability to make enough blood cells. One result is anemia, a shortage of red blood cells, which is part of the progressive fall in all blood cell types that is characteristic of the condition.
Cafe-au-lait spot
Skin findings such as cafe-au-lait spots and other areas of altered pigmentation are common and can be an early clue to the diagnosis.
Abnormal skin pigmentation
Many people with Fanconi anemia have changes in skin coloring, such as patchy areas of darker or lighter pigment. These skin pigmentation patterns are one of the features that can be present alongside the bone marrow and other findings of the condition.
Leukemia
There is also a markedly increased risk of acute myeloid leukemia, as well as solid tumors (especially head-and-neck squamous-cell cancers), driving the need for lifelong surveillance.
Microcephaly
A small head size (microcephaly) is among the congenital features that can be seen.
Chromosomal breakage induced by crosslinking agents
The defining laboratory test for Fanconi anemia looks for excessive chromosome breakage when cells are exposed to DNA-crosslinking chemicals like mitomycin C or diepoxybutane. FA cells break far more than normal, which confirms the diagnosis even before blood problems appear.
Triphalangeal thumb
Thumb and radial (forearm) bone anomalies are characteristic skeletal features; a triphalangeal or otherwise malformed thumb is a recognized example.
Aplasia/Hypoplasia of the radius
Fanconi anemia often affects the development of the thumb and the radius (the forearm bone on the thumb side), which may be small, malformed, or absent. These limb differences are among the most common physical signs of the condition.
Myelodysplasia
Fanconi anemia carries a high risk of myelodysplastic syndrome, a clonal disorder of the bone marrow, which is monitored for over time.
Bone marrow failure
Over time the bone marrow in Fanconi anemia stops making enough blood cells (bone marrow failure). This progressive failure is a central feature of the disease and is the main reason many people eventually need a stem cell transplant.
Squamous cell carcinoma
People with Fanconi anemia have a greatly increased lifetime risk of squamous cell carcinoma, especially of the head and neck (and also skin and genital areas). These cancers tend to appear at much younger ages than in the general population, so regular screening is important.
How it is diagnosed
Fanconi anemia
Diagnosed using: chromosome breakage test.
“Karyotype and chromosomal breakage test induced by Diepoxybutane confirmed her as a case of Fanconi Anaemia.”
Fanconi anemia
Diagnosed using: diepoxybutane analysis.
“Diepoxybutane (DEB) analysis is the preferred test for FA because other agents have higher rates of false-positive and false-negative results.”
Fanconi anemia
Diagnosed using: Fanconi anemia gene panel testing.
“Genetic findings prompted diagnostic revisions, including Fanconi anemia, Congenital Amegakaryocytic Thrombocytopenia, Shwachman-Diamond syndrome, and Diamond-Blackfan anemia.”
Treatment and management
What the research describes, not a recommendation. Treatment decisions belong with your clinician.
This covers treatments that appear in the published research mapped here. Investigational and experimental therapies are not included, so their absence is a boundary of this map, not a sign they do not exist.
hematopoietic stem cell transplantation
Hematopoietic stem cell transplantation, which replaces the failing bone marrow with healthy blood-forming stem cells from a donor, is described as the only treatment that can cure the bone marrow failure of Fanconi anemia. Bone marrow failure is the main cause of illness and death in the condition.
Used to help with: Fanconi anemia.
“…hematopoietic stem cell transplantation (HSCT) when…”
androgens
Androgens (such as oxymetholone or danazol) can boost blood counts in some patients and are used to ameliorate marrow failure, though they have side effects and are not curative.
Used to help with: Fanconi anemia.
“Androgens are an effective and safe option to ameliorate bone marrow failure in IBMFS.”
androgens
Androgens such as oxymetholone are male-type hormones that have been used in Fanconi anemia to raise blood counts when the bone marrow is failing. Long-term use can affect the liver, including the development of liver tumors, so it is used with monitoring.
Used to help with: Fanconi anemia.
“Two patients with Fanconi's anemia treated for 5 years with oxymetholone developed hepatic function abnormalities in association with hepatic…”
What changes how it shows up
Carrying the genetic change is not the whole story. The factors below are described in the research mapped here as changing whether, or how strongly, the condition appears. They modulate how the genotype is expressed; they do not, on their own, cause or cure it.
FANCA
Fanconi anemia can be caused by changes in any of several different genes. Changes in the FANCA gene account for most cases of the condition.
Described as modulating: Fanconi anemia.
“While FANCA mutations account for most FA cases, phenotypic overlap with other disorders complicates diagnosis.”
FANCC
The specific gene involved can influence how Fanconi anemia presents. The FANCC subtype has been linked with particularly severe blood and developmental problems.
Described as modulating: Fanconi anemia.
“Among its subtypes, FA complementation group C (FANCC) is associated with particularly severe hematologic and developmental manifestations.”
FAAP100
The gene involved can affect how severe Fanconi anemia is. Loss-of-function changes in the FAAP100 gene have been associated with some of the most severe patterns of developmental differences described in the condition.
Described as modulating: Fanconi anemia.
“The extensive developmental malformations of individuals with FAAP100 loss-of-function variants are among the most severe across previously described FA…”
How to read the evidence labels
Where this comes from
This guide is built from 19 published source(s). Every claim above links back to one of them. Click any source ID to read the original on PubMed.
Take it further
Printed, source-linked documents built from this condition's graph — ready to bring to an appointment or attach to a coverage request. Every claim carries its published source, the same as this guide.