FANC gene family

The genes in the FANC gene family provide instructions for producing proteins that are involved in a cell process known as the Fanconi anemia (FA) pathway. The main purpose of the FA pathway is to locate DNA damage and trigger its repair. The FA pathway is particularly responsive to a certain type of DNA damage known as interstrand cross-links (ICLs), which occur when two DNA building blocks (nucleotides) on opposite strands of DNA are abnormally attached or linked together. ICLs stop the process of making new copies of DNA, called DNA replication. ICLs can be caused by a buildup of toxic substances produced in the body or by treatment with certain cancer therapy drugs.

A main component of the FA pathway is the FA core complex, which is composed of eight FANC proteins and two additional proteins called Fanconi anemia-associated proteins (FAAPs). After DNA damage is identified, the FA core complex turns on (activates) two proteins, called FANCD2 and FANCI, by attaching a single molecule called ubiquitin to each of them (a process called monoubiquitination). The activation of these two proteins, which attach (bind) together to form the ID protein complex, attracts DNA repair proteins to the area of the damage so it can be repaired and DNA replication can continue.

Mutations in any of the FANC genes disrupt the process of repairing DNA damage, resulting in a condition called Fanconi anemia. This condition is characterized by a decrease in bone marrow function, an increased cancer risk, and physical abnormalities.

FANC gene mutations are sometimes associated with various types of cancer in people without the other features of Fanconi anemia. For example, mutations in the BRCA2, BRIP1, or PALB2 genes are associated with an increased risk of early-onset breast, ovarian, and pancreatic cancers.