Application Of PCR And DNA Microarray For Comprehensive Diagnosis Of Muscular Dystrophies

Muscular dystrophy (MD) is a group of highly heterogeneous muscle diseasescharacterized by progressive weakness and atrophy of skeletal muscles. The conditioncan be inherited in autosomal recessive, autosomal dominant or X-linked recessivepattern. Basing on clinical symptoms and onset, MD can be classified into eight types:pseudohypertrophy, limb-girdle, facioscapulohumeral, distal, dystrophy myotomic,congenital, Emery-Dreifuss, oculopharyngeal muscular dystrophy. Pseudohypertrophymuscular dystrophy consisting of Duchenne and Becker muscular dystrophy is themost common type. Currently, the diagnosis of muscular dystrophy is mainly basedon physical examination, family history and the results of muscle biopsy, increasedcreatine phosphokinase (CpK3), electromyography, electrocardiography.The highly complex clinical symptoms present as diverse symptoms of the sametype of MD and the ambiguous classification of different types of this condition. Forinstance, phenotype of LGMD2I ranges from severe which is similar to Duchennemuscular dystrophy with onset in the first years of life, to milder which more closelyresembles Becker muscular dystrophy with later onset (age6~23years). Anotherexample is the similarity between LGMD2B and Miyoshi muscular dystrophy, whichmay both present with muscle weakness and atrophy of distal and proximal musclesin young adults with slow progression. Researches have turned out that the twoconditions are both resulted by DYSF gene mutation. The heterogeneity complicatesthe diagnosis and management of MD, and is the bottleneck problem of therapyresearch of MD.As the development of gene location and function study, the molecularpathogenesis of MD is clarified gradually. The detection analysis of MD-related genescan be useful for the accurate clinical diagnosis, genetic consulting and prenataldiagnostic testing.In the study, we eatablished a set of genetic testing system of musculardystrophies using genetic analysis methods like multiplex PCR, realtime PCR andDNAmicroarray. Firstly, detect the26exons of the most commonly deleted regions inDMD gene using multiplex PCR. Secondly, by the method of realtime PCR, weestimate the corresponding exon copy numbers of the female relatives of patient withpseudohypertrophy muscular dystrophy. Thus, the exon status of DMD gene we areintersted of a female can be identified. Finally, DNA microarray is used to detect the 507gene locus mutations spreading over34genes which are related topseudohypertrophy, limb-girdle, distal, congenital, EDMD. Through the analysis, wecan detect the34MD-related genes simultaneously, economically and effectively,filling the blank arae in genetic diagnosis of MD. Also, we summarized and analysedthe molecular mechanism of MD, preparing for the new classification of MD basingon the pathogenesis.