Table 3.
FA genetic subtypes
| Complementation group (gene) | Approximate % of patients with FA | Chromosome location | Gene product | Exons |
|---|---|---|---|---|
| AR | ||||
| A (FANCA) | 65 | 16q24.3 | FANCA | 44 |
| C (FANCC) | 12 | 9q22.32 | FANCC | 22 |
| G (FANCG) | 12 | 9p13.3 | FANCG/XRCC9 | 14 |
| J (FANCJ) | <5 | 17q23.2 | FANCJ/BRIP1 | 25 |
| E (FANCE) | 4 | 6p21.31 | FANCE | 10 |
| F (FANCF) | 4 | 11p14.3 | FANCF | 1 |
| P (FANCP) | 2 | 16p13.3 | FANCP/SLX4 | 17 |
| D1 (FANCD1) | <1 | 13q13.1 | FANCD1/BRCA2 | 27 |
| D2 (FANCD2) | <1 | 3p25.3 | FANCD2 | 45 |
| I (FANCI) | <1 | 15q26.1 | FANCI | 38 |
| L (FANCL) | <1 | 2p16.1 | FANCL | 14 |
| M (FANCM)* | <1 | 14q21.2 | FANCM | 25 |
| N (FANCN) | <1 | 16p12.2 | FANCN/PALB2 | 14 |
| O (FANCO)* | <1 | 17q22 | FANCO/RAD51C | 12 |
| Q (FANCQ) | <1 | 16p13.12 | FANCQ/ERCC4 | 13 |
| S (FANCS)* | <1 | 17q21.31 | FANCS/BRCA1 | 24 |
| T (FANCT) | <1 | 1q32.1 | FANCT/UBE2T | 7 |
| U (FANCU) | <1 | 7q36.1 | FANCU/XRCC2 | 3 |
| V (FANCV) | <1 | 1p36.22 | FANCV/REV7 | 10 |
| W (FANCW) | <1 | 16q23.1 | FANCW/RFWD3 | 18 |
| X-linked recessive | ||||
| B (FANCB) | <1 | Xp22.2 | FANCB | 17 |
| AD | ||||
| R (FANCR)* | <1 | 15q15.1 | FANCR/RAD51 | 13 |
FA subtypes (complementation groups) A, C, and G account for most patients with FA. As can be noted from the table, many FA genes encode proteins that had previously been known by other names and have important roles in DNA repair.
*
Biallelic variants in FANCM, FANCO, and FANCS and heterozygous variants in FANCR/RAD51 produce FA-like disease3 (abnormalities overlap with those in patients with FA but are not sufficient to be classified as bona fide FA).