In other mouse models – the YG8R mouse, which expresses a transgenic human frataxin containing a (GAA) repeat expansion in a background null for murine frataxin (Al-Mahdawi et al., 2006), and repeat-expansion knock-in models [knock-in, knockout (KIKO)/knock-in, knock-in (KIKI)] (Miranda et al., 2002) – little or no cardiomyopathy is evident. Here, FXN is linked to cardiomyopathy.