Systematic Study Of The Clinical Diagnosis And Management For Duchenne Muscular Dystrophy

PART I DUCHENNE/BECKER MUSCULARDYSTROPHY IN SOUTHWEST OF CHINAObjective: To improve the diagnosis and management ofDuchenne/Becker muscular dystrophy (DMD/BMD) in Southwest ofChina.Methods: Clinical features of294DMD/BMD cases from Dec.2009to Dec.2011were collected. Genomic DNA was extracted using standardprocedures from the peripheral blood leukocytes, and multiple polymerasechain reaction (mPCR)+short tandem repeat (STR) were applied to detectDystrophin gene to identify genetic mutation.17cases weregastrocnemius muscle biopsies whose deletion mutations were notidentified. The standard procedure of cross-culture adaptation was used todevelop the Chinese version Pediatric Quality of Life InventoryTM3.0Neuromuscular Module (PedsQLTM3.0NMM).39patients and theirparents were investigated with the Chinese version scale. A11the patientswere followed up. Results: Among the294cases, exons and STR deletion ofDystrophin were detected in96cases (32.65%). And exons deletions incentral hot spot of recombination (exon44-51) were detected in82cases(85.42%). Among the17cases of gastrocnemius muscle biopsies,DMD/BMD was identified in14cases (82.35%).39questionnaires of theChinese version PedsQLTM3.0NMM were completed. It had acceptablepsychometric properties. The rates of item missing were less than1%.Total and all dimension’s Cronbach alpha coefficients were larger than0.7and the intraclass correlation coefficient (ICC) was larger than0.6. Theitem in the PedsQLTM3.0NMM was moderately and highly related withcorrelation coefficient of Spearman in its belonged domains than in otherdomains. Confirmatory factor analysis showed that the main indices ofgoodness of fit comparative fit index (CFI) were larger than0.9. Thescores in the cases with different disease severity had significantdifferences (P <0.05), and scores in communication and familydimensions were very low (P>0.05). Among the101DMD cases, only18were used prednisone with0.75mg/kg/d.Conclusion: The incidence of DMD/BMD is not uncommon inSouthwest of China. Application of mPCR+STR can improve theDystrophin gene detection accuracy, but the positive rate is low. Musclebiopsy is a good supplementary means to identify the disease. The mainfactor affecting quality of life (QOL) of DMD/BMD patients is illness severity. DMD/BMD patients are generally lack of good communicationand are bad family economy. It is very urgent to develop the diagnosis andmanagement of DMD/BMD guideline suitable for China’s nationalconditions. PART II PREDNISON TREATMENT FOR DUCHENNEMUSCULAR DYSTROPHY IN SOUTHWEST OF CHINAObjective: Duchenne muscular dystrophy (DMD) is an X-linkedrecessive disorder and is the most common form of muscular dystrophy.Glucocorticoids (GCs) are the only medication currently available thatslows the decline in muscle strength and function in patients with DMD.But it is not very clear which GCs to choose, when to initiate treatment,and how best to monitor manage side-efects. To perform a prospective,randomized, and controlled clinical trial comparing muscle strength,function, and quality of life (QoL) in patients with DMD under theguidelines in Southwest of China.Methods:66patients with DMD (aged4-12years) from Dec.2010 to Dec.2012were divided into GC group and the controls, receivingprednisone0.75mg/kg/d for6to12months, were evaluated by MedicalResearch Council Scale (MRC), the Chinese version Pediatric Quality ofLife InventoryTM3.0Neuromuscular Module (PedsQLTM3.0NMM),high-frequency ultrasound, and creatine kinase (CK). At the same time,side-efects were monitored.Results: For the patients in GC group after6to12months treatment,the muscle strength and function remained stable, which the differenceswere not significant (P>0.05) comparing to before treatment. Echoweakened and subcutaneous fat thickness reduced in high-frequencyultrasound, QoL improved, which the differences were significant (P <0.05) comparing to before treatment and with the controls. After6monthstreatment, the CK levels were significantly higher than those before and thecontrols, which the differences were significant (P <0.05). Thereafter CKlevels gradually declined, but they did not return to the normal ranges. Allthe results of the controls decreased significantly with the progression ofthe disease, which the differences were statistically significant (P <0.05)comparing to before treatment. Side-effects of most patients with DMDwere not significant in the clinical trial process. The weight, height, andblood pressure in the two groups were not different significantly (P>0.05).Conclusion: Prednisone0.75mg/kg/d is suitable for the patients withDMD in Southwest of China for medium-and long-term treatment, and it is fewer side-effects. The change of CK levels is valuable for DMD diagnosis.But it is no stable and can not be used as the objective indicators to assessdrug efficacy. High-frequency ultrasound not only be able to provide anobjective basis for the early diagnosis of the disease and disease follow-up,but also be as objective indicators to assess the drug efficacy of DMD.These results will provide constructive guidance for early diagnosis, earlyintervention and effective evaluation and side-effects monitoring of DMDin the southwest of China. PART III THE EXPRESSION AND CLINICALSIGNIFICANCE OF MUSCLE-SPECIFIC MICRORNASIN SERUM OF DUCHENNE MUSCULAR DYSTROPHYObjective: Duchenne muscular dystrophy (DMD) is a lethalX-linked disorder caused by mutations in the dystrophin gene, whichencodes a cytoskeletal protein, dystrophin. Creatine kinase (CK) isgenerally used as a blood-based biomarker for muscular disease includingDMD, but it is not always reliable since it is easily affected by stress to the body, such as exercise. Therefore, more reliable biomarkers of musculardystrophy have long been desired. MicroRNAs (miRNAs) are small,～22nucleotide, noncoding RNAs which play important roles in the regulationof gene expression at the post-transcriptional level. Recently, it has beenreported that miRNAs exist in blood. In this study, we hypothesized thatthe expression levels of specific serum circulating miRNAs may be usefulto monitor the pathological progression of muscular diseases, andtherefore explored the possibility of these miRNAs as new biomarkers forDMD.Methods: Using SYBR green real-time quantitative reversetranscription-PCR, we detected the expression of muscle-specific miRNAsin39patients with DMD and36normal control subjects from Dec.2010to Dec.2012. Furthermore, we analyzed the associations betweenmuscle-specific miRNAs expression and clinical features of patients withDMD comparing to creatine kinase (CK).Results: Muscle-specific miRNAs, especial miRNA-206, weresignificantly overexpressed in serum of DMD relative to normal control (P<0.01), and its sensitivity and specificity were significantly higher than CKlevels, as a blood-based biomarker for DMD. Unlike CK levels, expressionlevels of these miRNAs in serum of DMD are little influenced by gender,age, exercise, and stress. They were highly correlated with the differentstages of DMD progression. Conclusion: Muscle-specific miRNAs, especial miRNA-206, are newand valuable biomarkers for the diagnosis of DMD and possibly also as anew target for therapeutic interventions in humans. It provides a new ideato explore effective cure for DMD and has important implications forguidance related basic and clinical research.