Clinical,muscle pathology and gene mutation characteristics of congenital myopathy with tremor
Objective To summarize and discuss the clinical manifestations,muscle pathology and gene mutation characteristics of congenital myopathy with tremor and to improve clinicians'understanding of the disease.Methods The clinical data of a patient of congenital myopathy with tremor who visited Qilu Hospital of Shandong University in April 2021 were reported.Enzyme histochemical staining and immunohistochemical staining were performed on the muscle tissues of the patient,and the expression level of slow skeletal myosin binding protein-C(sMyBP-C)and mitochondrial DNA copy numbers were detected by Western blotting and quantitative real-time polymerase chain reaction.The literatures of congenital myopathy with tremor reported previously were reviewed and patients reported were summarized.Results The proband is a 35 years old male,whose clinical symptoms occurred from childhood,mainly manifested as irregular muscle vibration of the limbs and exercise intolerance,with mild proximal limb muscle weakness.Muscle biopsy showed mild myogenic damage with abnormal mitochondrial changes,and gene detection showed MYBPC1 gene c.788T＞G heterozygous mutation.Further detection showed that the expression level of sMyBP-C was significantly reduced,and the number of mitochondrial DNA copies was increased in the patient.The diagnosis of congenital myopathy with tremor was clear,and the symptoms did not progress during long-term follow-up.The clinical characteristics of 26 patients from this family and 10 families previously reported were summarized,and the results indicated that tremor was a prominent clinical manifestation of this disease,combined with mild to moderate muscle weakness,which could be accompanied with varying degrees of myasthenia,delayed gross motor development and skeletal joint malformation.The symptoms usually had no progress or chronic progress.Muscle biopsy usually indicated myogenic damage,including type Ⅰ fiber predominancy,type Ⅰ fiber atrophy and central cores in type Ⅰ fibers,which may be accompanied by mild mitochondrial abnormalities.The c.788T＞G mutation in the MYBPC1 gene was a hotspot mutation of congenital myopathy with tremor.Conclusions For early-onset tremor of unknown reason with muscle weakness,hypotonia,delayed gross motor development and skeletal joint malformation,it is necessary to consider the possibility of congenital myopathy with tremor,and to further perform electromyography,muscle biopsy,and gene detection for a clear diagnosis.Muscle biopsy usually indicates myogenic damage,and the c.788T＞G mutation in the MYBPC1 gene is a hotspot mutation of the disease.
TremorMuscular diseasesMyosin-binding protein CBiopsy
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