Myotonic Dystrophy: Muscle Pathological, Electrophysiological, Myogenic Relation Factors' MRNA Expression And Familial Cases Review

Objectives 1.To study the clinical,muscle pathological,electrophysiological features: and the expression of myostatin and 4 myogenic regulation factors(MRFs:myogenin, myoD,myf4 and MRF4)in the skeletal muscle of myotonic dystrophy(DM)patients. Methods Retrospective analysis and semi-quantitative RT-PCR were used.Results1.Among 14 cases,myopathic changes of DM were found in 5,and end-brush nerve damage in 9.Sarcoplasmic masses were shown in 5.By ATPase stainning,we found myogenic type-grouping with 6 biopsies having typeⅠpredominance,5 typeⅡ, and normal distribution in 3.2.EMG feature:the rates of fibrillation potentials and positive sharp spontaneous potentials were lower,but the degree of motor unit potentials(MUP)duration shortening higher,and the amplitude of MUP lower in the cases with typeⅠpredominance(0 vs 70.8%,x~2=14.2351,P=0.000;0 vs 44.4%,x~2=8.2540,P=0.004; 37.1%vs 21.9%,t=2.67,P=0.011;386.2μV vs 471.0μV,t=2.16,P=0.047).3.The average incidence rate of familial DM in Chinese was 0.3817.The average age of onset was 27,the survival period after onset was 23,and the average life span of patients and their first relatives was about 50.In addition to muscle,the organ or tissue involved most was crystalline lens.The onset age of five successive generation was 52.8,31.6,27.4,19.8,and 10.3,respectively.And marked genetic anticipation was exhibited.4.Increased expression level of myostatin and myogenin gene mRNAs had been noted in skeletal muscle of myotonic dystrophy patients compared to that of healthy controls(2.25±1.043 vs 0.34±0.150,P=0.01;0.92±0.883 vs 0.41±0.119,P= 0.02).The decreased expression level of MyoD gene mRNA has been noted(0.27±0.114 vs 0.79±0.136,P=0.001).Conclusions There was no specific muscular pathologic change in DM.In patients with DM the severity of the electromyographical changes were related to the predominant fibre type.In Chinese,DM shortened the patients' and relatives' life span.The expression of myostatin and MRFs gene mRNA was different in skeletal muscle of DM patients and healthy controls.