The Clinical Features, Immunostaining and Genetic Study in Duchenne/Becker Muscular Dystrophy

Seo, Chang Deok; Lee, Yoon Jung; Lee, Eun Hye; Jeong, Min Hee; Yum, Mi Sun; Ko, Jung Min; Yoo, Han Wook; Ko, Tae Sung

Abstract

PURPOSE: This retrospective study was designed to know the relation between clinical features, genetics, and immunostaining findings among children with Duchenne muscular dystrophy (DMD)/Becker muscular dystrophy (BMD) and the validity of the diagnostic tools for muscular dystrophy.
METHODS
The medical records and computerized databases of 93 patients diagnosed with DMD/BMD from June 1989 to December 2008 were reviewed retrospectively. Demographic characteristics including clinical features, serum creatinine kinase(CK) level, electromyogram(EMG) and nerve conduction velocity(NCV), muscle biopsy, immunochemical staining for dystrophin, and the deletion of dystrophin gene were analyzed. We calculate the concordance rate between type of frame (in or out of frame) and phenotype.
RESULTS
58(62%) children were diagnosed with DMD, 13(14%) BMD, 19(20%) unclassified dystrophy, and 3(3%) DMD/BMD carriers. The mean age of symptom onset was 5.0+/-3.5 years(range, 1-17). 46(49%) children presented gait disturbance and 35(37%) elevation of liver enzymes. The mean value of serum CK enzyme was 14,758+/-11,792 IU/L (range, 633-61,349). There was no dystrophin in the immunochemical stain among 48 DMD children and at least partial or incomplete dystrophin among 10 BMD children. 28/54(51%) children had dystrophin gene deletion in multiplex PCR and 13/14(92%) in Multiplex Ligation-dependent Probe Amplification(MLPA). The loss of heterozygosity was shown in 2 children by MLPA. The overall concordance rate between type of frame(in or out of frame) and phenotype was 95% in this study.
CONCLUSION
Despite of small population, this finding indicates that the determination of type of frame (in or out of frame) by MLPA may be helpful in differential diagnosis of DMD/BMD. In addition, we surmise that the detection of carrier by MLPA is helpful in genetic counseling.