A rare genetic neuromuscular disease caused by a mutation in HSPB8 gene, characterized by length-dependent axonal motor neuropathy predominantly affecting the lower limbs, in combination with a myopathy with morphological features of myofibrillar myopathy with aggregates and rimmed vacuoles. The disease is myopathy, myofibrillar, 13, with rimmed vacuoles (MONDO_0976133, a Monarch Disease Ontology term). Also known as: HSPB8-associated autosomal dominant rimmed vacuolar myopathy, HSPB8-related autosomal dominant distal axonal motor neuropathy-myofibrillar myopathy syndrome, MFM13, autosomal dominant distal axonal motor neuropathy-myofibrillar myopathy syndrome, limb-girdle rimmed vacuolar myopathy, rimmed vacuoles myopathy.