Reducing body myopathy (RBM) is a rare, sometimes fatal, X-linked disorder characterized by progressive muscle weakness and the presence of intracytoplasmic aggregates in histological muscle sections which exert a reducing activity on nitro-blue tetrazolium (NBT) staining. The causative gene for RBM is FHL1 encoding four and a half LIM domains.
Four and a half LIM protein 1 gene mutations cause four distinct human myopathies: a comprehensive review of the clinical, histological and pathological features.