Microarray-based mutation detection in thedystrophingene

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Abstract
Duchenne and Becker muscular dystrophies (DMD and BMD) are X‐linked recessive neuromuscular disorders caused by mutations in the dystrophin gene affecting approximately 1 in 3,500 males. The human dystrophin gene spans>2,200 kb, or roughly 0.1% of the genome, and is composed of 79 exons. The mutational spectrum of disease‐causing alleles, including exonic copy number variations (CNVs), is complex. Deletions account for approximately 65% of DMD mutations and 85% of BMD mutations. Duplications occur in approximately 6 to 10% of males with either DMD or BMD. The remaining 30 to 35% of mutations consist of small deletions, insertions, point mutations, or splicing mutations, most of which introduce a premature stop codon. Laboratory analysis of dystrophin can be used to confirm a clinical diagnosis of DMD, characterize the type of dystrophin mutation, and perform prenatal testing and carrier testing for females. Current dystrophin diagnostic assays involve a variety of methodologies, including multiplex PCR, Southern blot analysis, multiplex ligation‐dependent probe amplification (MLPA), detection of virtually all mutations‐SSCP (DOVAM‐S), and single condition amplification/internal primer sequencing (SCAIP); however, these methods are time‐consuming, laborious, and do not accurately detect duplication mutations in the dystrophin gene. Furthermore, carrier testing in females is often difficult when a related affected male is unavailable. Here we describe the development, design, validation, and implementation of a high‐resolution comparative genomic hybridization (CGH) microarray‐based approach capable of accurately detecting both deletions and duplications in the dystrophin gene. This assay can be readily adopted by clinical molecular testing laboratories and represents a rapid, cost‐effective approach for screening a large gene, such as dystrophin. Hum Mutat 0, 1–9, 2008.