Fanconi anemia definition
Fanconi anemia (FA) is a rare disorder with diverse symptoms. Because the clinical symptoms vary considerably, and may be absent altogether, the FA diagnosis critically depends on a positive result from a chromosomal breakage test in which cells are exposed to a cross-linking agent such as diepoxybutane or mitomycin C.
The gene symbols for FA genes carry the root FANC#, followed by a letter, to be assigned in alphabetical order in order of discovery. If a gene with an existing approved symbol is identified as a FA causing gene, the original gene symbol is usually maintained and an appropriate FANC# gene symbol may be assigned as a synonym.
Genes encoding proteins that are supposed to function in the FA pathway, but without any patients identified to date who carry mutations in these genes, will have symbols with the root FAAP (for Fanconi anemia associated protein) followed by a number.
However, if the gene already has an approved gene symbol, the FAAP# designation will be added as a synonym to the gene record. If the gene has no previously approved symbol then an FAAP# symbol will be approved. If pathogenic mutations in such genes are subsequently shown to cause FA in humans, a new FANC# designation will be assigned, possibly as a synonym. Investigators may prefer to use the FANC# designations in their reports, but should always make reference to the approved symbol where applicable.
Note: FANCH is not listed because complementation group H has been withdrawn. The letter K has been missed out, for practical reasons, as FANCK confuses with FANCA when pronounced; likewise, if the series extends past FANCT, FANCU will be missed out as it could be confused with FANCQ. Complementation group D has been split into D1 and D2, associated to BRCA2 and FANCD2, respectively.