Female Carriers of Duchenne Muscular Dystrophy

Dystrophinopathy, caused by mutations in the DMD gene, presents with variable clinical phenotypes ranging from the severe Duchenne muscular dystrophy (DMD) to the milder Becker muscular dystrophy(BMD) forms. DMD is a recessive X-linked form of muscular dystrophy. Two-thirds of mothers of affected males are thought to be DMD carriers. Approximately 2.5-7.8% of female DMD carriers have muscle weakness and are categorized as manifesting DMD carriers. The symptoms of female carriers of DMD range from mild muscle weakness to severe gait problems. The most commonly presented symptom is mild proximal muscle weakness, which is often asymmetric and progressive, but shows variable clinical spectrum with BMD of more severe DMD-like phenotype. Atypical presentations in manifesting carriers are myalgia or cramps without limb weakness, isolated cardiomyopathy and camptocormia. Multiplex PCR and MLPA analysis are common techniques to identify mutations in the DMD gene. Relationship between X-chromosome inactivation and clinical severity is not clear. Female carriers of DMD are not less common, and they have an important role of birth of a male DMD.