As we have shown a link between α-actinin-3 deficiency and muscle performance in athletes and the general population we are now examining whether an individual has α-actinin-3 or not will influence the progression or severity of muscle diseases using both our mouse model and human association studies. We are also investigating the changes in metabolism in α-actinin-3 deficient muscle in more detail, in particular looking at the effects of having or not having α-actinin-3 on diabetes and obesity.