Neuromusculoskeletal DisorderThin FilamentsPossible CauseInfant SiblingsFatal CourseMedicinePhysiologyPediatricsNeurologyAnatomyNeuropathologyNeuromuscular PathologyNeuromuscular DisordersFatal Infantile HypotoniaHealth Sciences
Two infant siblings (male and female) manifested extreme hypotonia and flaccidity at birth and had a rapidly fatal course. In each, rod-like structures were demonstrated within a variety of skeletal muscles, and accumulations of thin filaments were seen in numerous muscle fibers. The possibility exists that this represents a severe and rapidly fatal form of nemaline myopathy that should be included in the differential diagnosis of infantile hypotonias.