Evolution of Molecular Diagnosis of Duchenne Muscular Dystrophy
Afaf Ben Itto
&Khalil Hamzi
&Hanane Bellayou
&Mohammed Itri
&Ilham Slassi
&Sellama Nadifi
Received: 14 January 2013 / Accepted: 23 January 2013 / Published online: 5 February 2013
#Springer Science+Business Media New York 2013
Abstract Duchenne muscular dystrophy (DMD) is the commonest of the muscular dystrophies. The DMD gene (DMD) is the biggest human gene and the most common molecular defect in the DMD gene, accounting for approx- imately 65 % of cases of DMD, is the deletion of one or more exons. The most basic method still in regular use involves multiplex PCR of the exons, known to be most commonly deleted. The multiplex is relatively simple.
Quantitative analysis of all exons of the gene and multiplex ligation-dependent probe amplification have brought about an improvement in mutation detection rate, as they will detect all exon scale deletions as well as duplications, wide- ly used to detect exonic and intronic mutations. As a sensi- tive and discriminative tool, MLPA can be used for prenatal testing. A more recent development in quantitative analysis is the use of oligonucleotide-based array comparative ge- nomic hybridization.
Keywords Duchenne muscular dystrophy (DMD) . Multiplex PCR . Quantitative analysis . Comparative genomic hybridization
Dear Editor,
Duchenne muscular dystrophy (DMD) is the commonest of the muscular dystrophies affecting 1 in 3,500 live male births (Biggar et al.
2006). DMD is an X-linked recessive disease thataffects boys. The disease results from degeneration and loss of muscle fibres (Biggar et al.
2006). The natural history of DMDincludes the affected boys typically becoming wheelchair- bound starting at the age 12 (Daftary et al.
2007). The DMDgene (DMD) is the biggest human gene (2.5 Mbp; Fig
1).Once the gene was identified, it was established that affected boys were lacking dystrophin, the protein product of the gene (Daftary et al.
2007). The most common molec-ular defect in the DMD gene, accounting for approximately 65 % of cases of DMD, is the deletion of one or more exons and duplication accounts for 6–10 % of cases (Daftary et al.
2007). The minimum level of diagnostic testing that should
be undertaken is a screen that detects the majority of exonic deletions. The most basic method still in regular use involves multiplex PCR of the exons known to be most commonly deleted (Chamberlain et al.
1988) (Fig.2).The multiplex is relatively simple; however, it does not detect duplications, does not characterise all deletion break- points and cannot be used for carrier testing of females. Also, multiplex PCR does not allow detection of intronic mutations.
Quantitative analysis of all exons of the gene has brought about an improvement in mutation detection rate, as they will detect all exon scale deletions as well as duplications. They also fully delineate the exon boundaries of detected mutations and detect mutations in carrier females. Of the quantitative methods available, multiplex ligation-dependent probe amplification (MLPA) is now the most widely used to detect exonic and intronic mutations; as a sensitive and discriminative
A. B. Itto (*):
M. Itri:
S. NadifiNeuropediatrics Department, Ibn Rochd Hospital, Casablanca, Morocco
e-mail: [email protected] I. Slassi
Neurology Department, Ibn Rochd Hospital, Casablanca, Morocco K. Hamzi
:
H. BellayouGenetics Department, Ibn Rochd Hospital, Casablanca, Morocco J Mol Neurosci (2013) 50:314–316
DOI 10.1007/s12031-013-9971-1
Fig. 2 Analysis of dystrophin gene by multiplex PCR (Bellayou et al.2009) Fig. 3 MLPA results of the
three cases showing non- contiguous duplication and deletion (Murugan et al.2010) Fig. 1 Schematic representation of the 79 exons of dystrophin gene explains the reading frame rule of Bellayou et al. (2009)
J Mol Neurosci (2013) 50:314–316 315
tool, MLPA can be used for prenatal testing (Abbs et al.
2010) (Fig. 3).
An important point to note is that with both methods described so far, any apparent mutation indicated by an ab- normal reading from a single probe must be confirmed by an alternative method, to account for the possibility of a single nucleotide polymorphism under a probe or primer binding site. A more recent development in quantitative analysis is the use of oligonucleotide-based array comparative genomic hybridisation (del Gaudio et al.
2008).References
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