A rare congenital muscle disorder involving muscle weakness and wasting. The term minicore comes from the small core structures that occur in the muscle tissue. There are four subgroups of the disorder: classic form (rigid spine syndrome), progressive form with hand involvement, antenatal form with arthrogryposis multiplex congenital and the ophthalmoplegic form. The progressive form with hand involvement is less severe than the classic form with breathing problems and scoliosis usually absent or mild. It is distinguished by the presence of hyperlaxity. The severity of symptoms is variable. See also Minicore myopathy, moderate, with hand involvement