Late-onset distal myopathy, Markesbery-Griggs type is a rare, genetic, non-dystrophic myofibrillar myopathy disorder characterized by late-adult onset of distal and/or proximal limb muscle weakness with initial involvement of posterior lower leg muscles, medial gastrocnemius and soleus. Patients present with ankle weakness followed by weakness of finger and wrist extensors and later on of proximal muscles. Ambulation is usually preserved. Late-onset associated cardiomyopathy and/or neuropathy has been reported in a minority of cases. The disease is Monarch Disease Ontology identifier MONDO_0012277 (myofibrillar myopathy 4). Also known as: LDB3 myofibrillar myopathy (disease), ZASP-related myofibrillar myopathy, myofibrillar myopathy (disease) caused by mutation in LDB3, myofibrillar myopathy type 4, myopathy, myofibrillar, type 4, zaspopathy.