Associations between clinical phenotype (muscle weakness, dilated cardiomyopathy) and dystrophin abnormalities in muscle tissue among definite carriers of Duchenne (DMD) and Becker muscular dystrophy (BMD) were investigated.
We report three cases who presented with only mild or no muscle weakness but had elevated serum creatine kinase activity and dystrophin immunolabelling indistinguishable from normal, making a pathological diagnosis difficult.
Abnormalities of dystrophin are a common cause of muscular dystrophy and testing for dystrophin gene or protein has become a part of routine diagnostic evaluation of patients who present with progressive proximal muscle weakness, high serum creatine kinase concentrations, and histopathological evidence of a dystrophic process.
We have previously shown in a large X-linked pedigree that a deletion removing the dystrophin muscle promoter, the first muscle exon and part of intron 1 caused a severe dilated cardiomyopathy with no associatedmuscle weakness.
We recently described a family where a deletion of the dystrophin gene was associated with a severe dilated cardiomyopathy without skeletal muscle weakness.
It is speculated that overexpression of the dystrophin-related protein in regenerating muscle fibers may contribute to the slow progression of muscle weakness or atrophy.
Ten females presenting with muscle weakness and a raised serum creatine kinase revealed abnormalities in the expression of dystrophin in their muscle biopsies and were diagnosed as manifesting carriers of Xp21 Duchenne/Becker muscular dystrophy.
An apparently identical deletion in one family gave classical BMD in two brothers (presenting in their teens) and only very mild muscle weakness in their 86-year-old great-great-uncle.
The most common type of Charcot-Marie-Tooth disease is caused by a duplication of PMP22 leading to dysmyelination, axonal loss and progressive muscle weakness (CMT1A).
Charcot-Marie-Tooth disease type 1A is an autosomal dominant polyneuropathy due to peripheral myelin protein 22 gene duplication and characterized by slowly progressive distal limb muscle weakness, atrophy and sensory loss with foot deformities.
Heterozygous PMP22-transgenic rats develop muscle weakness and gait abnormalities as well as reduced nerve conduction velocities and EMG abnormalities, which closely resemble recordings in patients with CMT1A.
The presence of α-amylase resistant PAS-positive material in skeletal muscle biopsy of patients with slowly progressive limb girdle muscle weakness should prompt the search for GYG1 mutations.
Myoadenylate deaminase deficiency with progressive muscle weakness and atrophy caused by new missense mutations in AMPD1 gene: case report in a Japanese patient.
Myoadenylate deaminase deficiency with progressive muscle weakness and atrophy caused by new missense mutations in AMPD1 gene: case report in a Japanese patient.