SLX4 and Friedreich ataxia: Processing/resolution of the HJs is promoted by various redundant enzymes including the BLM–TOPOIII-RMI1–RMI2 complex (125) and the endonucleases GEN1 (GEN endonuclease 1) (126), the MUS81–EME1 complex (123,124) and the SLX1–SLX4 complex (127) (SLX4 is also known as FANCP in FA).