The daughter of a carrier mother has a 50% chance of being a carrier and a 50% chance of having two normal copies of the gene. In all cases, an unaffected father either passes a normal Y to his son or a normal X to his daughter. Female carriers of an X-linked recessive condition, such as DMD, can show symptoms depending on their pattern of X-inactivation.DMD is extremely rare in females (about 1 in 50,000,000 female births). It can occur in females with an affected father and a carrier mother, in those who are missing an X chromosome, or those who have an inactivated X chromosome (the most common of the rare reasons). The daughter of a carrier mother and an affected father will be affected or a carrier with equal probability, as she will always inherit the affected X-chromosome from her father and has a 50% chance of also inheriting the affected X-chromosome from her mother.Disruption of the blood-brain barrier has been seen to be a noted feature in the development of DMD. Diagnosis
Genetic counseling is advised for people with a family history of the disorder. DMD can be detected with about 95% accuracy by genetic studies performed during pregnancy. Creatine kinase (CPK-MM) levels in the bloodstream are extremely high. An electromyography (EMG) shows that weakness is caused by destruction of muscle tissue rather than by damage to nerves.
This functional, yet truncated, form of dystrophin gave rise to the notion that shorter dystrophin can still be therapeutically beneficial. Concurrently, Kole et al. had modified splicing by targeting pre-mRNA with antisense oligonucleotides (AONs). Kole demonstrated success using splice-targeted AONs to correct missplicing in cells removed from beta-thalassemia patients Wiltons group tested exon skipping for muscular dystrophy. Gene therapy
Researchers are working on a gene editing method to correct a mutation that leads to Duchenne muscular dystrophy (DMD). Researchers used a technique called CRISPR/Cas9-mediated genome editing, which can precisely remove a mutation in the dystrophin gene in DNA, allowing the bodys DNA repair mechanisms to replace it with a normal copy of the gene. The benefit of this over other gene therapy techniques is that it can permanently correct the "defect" in a gene rather than just transiently adding a "functional" one.Genome editing through the CRISPR/Cas9 system is not currently feasible in humans. However, it may be possible, through advancements in technology, to use this technique to develop therapies for DMD in the future. In 2007, researchers did the worlds first clinical (viral-mediated) gene therapy trial for Duchenne MD.Biostrophin is a delivery vector for gene therapy in the treatment of Duchenne muscular dystrophy and Becker muscular dystrophy. References
Further reading
Birnkrant DJ, Bushby K, Bann CM, Apkon SD, Blackwell A, Brumbaugh D,  et al. (March 2018). "Diagnosis and management of Duchenne muscular dystrophy, part 1: diagnosis, and neuromuscular, rehabilitation, endocrine, and gastrointestinal and nutritional management". Lancet Neurol. 17 (3): 251–267. doi:10.1016/S1474-4422(18)30024-3. PMC 5869704. PMID 29395989.