When possible, please notify our laboratory 24-48 hours in advance of sending a sample for this test.
Blood is exposed to Mitomycin C (MMC) and/or Diepoxybutane (DEB) which leads to an increased rate of chromosome breakage in patients with Fanconi anemia (FA). Chromosome breakage after exposure to MMC and/or DEB is diagnostic for FA but cannot determine the Fanconi anemia complementation group. Additional send-out testing would be necessary to determine a specific gene associated with the specific complementation group; there are at least 16 different genes known to be associated with FA.
Test details and complementary testing
Our laboratory currently offers two methods of inducing chromosome breakage in lymphocyte cultures for the diagnosis of Fanconi anemia: MMC-induced and DEB-induced Breakage Study.
- Three cultures are initiated for each patient: 1) 72-hour PHA-stimulated culture with MMC, 2) 72-hour PHA-stimulated culture with DEB, and 3) 72-hour PHA-stimulated culture. The 72-hour culture without MMC or DEB is used to measure spontaneous breakage as opposed to chemically induced breakage. Non-Fanconi anemia controls for each method used must also be set up to establish a base-line of chromosome breakage for the laboratory. Each of the above cultures must be scored for any chromosome aberrations.
- While chromosome breakage studies are critical in the diagnosis of Fanconi anemia in the affected patient, testing for other at-risk family members requires knowledge of the specific disease-causing mutations in the family. These mutations cannot be identified using the chromosome breakage or other studies performed in our laboratory. Please contact a Laboratory Director or Genetic Counselor should you have questions.