Fanconi anemia laboratory findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:
Overview
The diagnosis of Fanconi anemia is not based on routine laboratory tests; it must be considered and tested for using chromosome breakage in blood or fibroblasts, or germline mutation analysis. Siblings who do not apparently have Fanconi anemia need to be screened for occult Fanconi anemia.
Any patient with single-lineage or multi-lineage cytopenias without known cause who also has one or more congenital malformations strongly associated with FA.[1]
Laboratory findings consistent with the diagnosis of Fanconi Anemia include Pancytopenia, Chromosomal breakage test positive, and Flow cytometry shows arrest in G2/M phase.
Laboratory Findings
- Anemia normocellular or hypercellular bone marrow
- The screening laboratory test for this defect involves assessment of chromosomal breakage upon exposure of cells to diepoxybutane (DEB) or mitomycin C (MMC)
- Gastrointestinal Atresias, imperforate anus, TE fistula, malrotation,.
- Kidney – Abnormal, ectopic, horseshoe, hypoplastic, or absent kidney; hydronephrosis.
Testing for FA is absolutely and urgently indicated in any child or young adult meeting any of the following criteria:
●Two or more moderate to severe cytopenias (absolute neutrophil count [ANC] <1000/microL, platelet count <50,000/microL, hemoglobin <10 g/dL with absolute reticulocyte count <40,000/microL), persistent for more than two weeks, and a hypocellular bone marrow (<25 percent of normal cellularity) in the absence of malignancy, cytotoxic therapy, or other known cause.
●Findings that satisfy criteria for the VACTERL-H association or multiple other malformations such as short stature, café-au-lait spots, or hypospadias, which are strongly associated with FA.
●Relative of a known patient with FA who is being evaluated as a potential donor for HCT.
CBC Count, Chromosome Breakage Test, and Flow Cytometry
CBC count
In Fanconi anemia, the complete blood count (CBC) may reveal trilineage pancytopenia or may only show RBCs that are macrocytic for age. Macrocytosis, thrombocytopenia, and/or leukopenia may precede full-blown aplasia.
Chromosome breakage test
Chromosome breakage is usually examined in short-term cultures of peripheral blood T-cell mitogen–stimulated lymphocytes in the presence of DNA cross-linkers, such as DEB or MMC. These agents lead to increased numbers of breaks, gaps, rearrangements, and quadraradii in Fanconi anemia homozygote cells.
Some patients may have hematopoietic somatic mosaicism, with correction of the Fanconi anemia defect in the blood. In these cases, skin fibroblasts may be needed for the chromosome breakage test.
Flow cytometry
Flow cytometry of Fanconi anemia cells cultured with nitrogen mustard and other clastogens demonstrates an arrest in G2/M.
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- An elevated/reduced concentration of serum/blood/urinary/CSF/other [lab test] is diagnostic of [disease name].
- [Test] is usually normal among patients with [disease name].
- Laboratory findings consistent with the diagnosis of [disease name] include:
- [Abnormal test 1]
- [Abnormal test 2]
- [Abnormal test 3]
- Some patients with [disease name] may have elevated/reduced concentration of [test], which is usually suggestive of [progression/complication].
References
- ↑ Giampietro PF, Adler-Brecher B, Verlander PC, Pavlakis SG, Davis JG, Auerbach AD (1993). "The need for more accurate and timely diagnosis in Fanconi anemia: a report from the International Fanconi Anemia Registry". Pediatrics. 91 (6): 1116–20. PMID 8502512.
| Suspected clinical FA | |||||||||||||||||||||||||||
| Chromosome breakage test on peripheral film | |||||||||||||||||||||||||||
| Ambiguous | |||||||||||||||||||||||||||
| Repeat Chromosome breakage test | |||||||||||||||||||||||||||
| Abnormal | Normal | ||||||||||||||||||||||||||
| Highly suspected FA | Not highly suspected FA | ||||||||||||||||||||||||||
| Chromosome breakage test on skin fibroblast | |||||||||||||||||||||||||||
| Abnormal | Normal | ||||||||||||||||||||||||||
| Consider other IBMFS | |||||||||||||||||||||||||||
| Diagnosis of FA | |||||||||||||||||||||||||||
| Genetic testing for Korean mutations FANCAexon 27 & 37 FANCGintron 3 & exon 8 | |||||||||||||||||||||||||||
| Other FA associated genes | |||||||||||||||||||||||||||