Duchenne Muscular Dystrophy (DMD) and Becker Muscular Dystrophy (BMD) Dystrophinopathies are diseases that are caused due to mutation in the dystrophin-coding gene, including Duchenne Muscular Dystrophy (DMD) and Becker Muscular Dystrophy (BMD). They are one of the most common neuromuscular diseases in Hong Kong. According to a local study, the prevalence of dystrophinopathies (including DMD and BMD) in Hong Kong is around 1.03 per 10 000 males. The global prevalence is 7.1 per 100,000 males. DMD is one of the most severe types of muscular dystrophies. It is an early onset disease which causes progressive muscle degeneration. Patients start to have symptoms since childhood.
DMD and BMD are inherited diseases that can be passed on to the next generation through carriers of the defective gene. As they are X-linked recessive diseases, two copies of the defective gene (located on the X-chromosome) are required for the disease to develop. Therefore, mainly males are affected. Female cases of DMD patients are rare but they can be carriers of the defective gene and have a 50% chance of passing on the defective gene to their children.
DMD is caused by mutations in the DMD gene, which encodes the dystrophin protein. The most common mutations include large deletions and large duplications. Other mutations include point mutations and insertions.
DMD can be tested by numerous methods, including blood tests, muscle biopsy, CGH-array, multiplex PCR, direct sequencing, and deletion/duplication analysis. Pangenia Genomics offers deletion/duplication analysis that accurately detects the number of copies of the DMD gene, i.e. find out if the gene or part of the gene is deleted or duplicated. It can be used for carrier screening as well.