XIRP1 and myofibrillar myopathy: In a previous study using immunolocalization of several myofibrillar proteins in myofibrillar myopathy (MFM) patients, we found that in MFM patients, some Z-disc proteins such as α-actinin, titin, SYNPO2/myopodin and SYNPO2L/tritopodin were rather stable Z-disc components, whereas other proteins (filamin C, myotilin, ZASP, Xin and XIRP2) revealed striking alterations in these pathological situations [45].