Duchenne muscular dystrophy

From Ganfyd

A genetically heterogeneous muscular dystrophy affecting males (predominantly) due to mutations in the encoding for the muscle fibre protein dystrophin at Xp21.2. Becker muscular dystrophy and a few other rarer myopathies are also caused by mutations of the same gene. Females can be affected by say X chromosome translocations. To complicate matters further mutations at the 12q21 region of the genome could affect myogenic factors such as MYF6 or MYF5 which might modify the presentation. Female carriers might have mild signs. As the genetics, although complex, are fairly well understood, multiple genetic therapies are in phase 1 and phase 2 trials at present.

Clinical diagnosis

Usually straight forward in males:

• Gait difficulty beginning at age three
• Progressive myopathic weakness
• Pseudohypertrophy of calves
• Possibly learning difficulties
• Very high serum level creatine kinase
• Electromyography
• Muscle biopsy(take care as histology has to be interpreted in clinical context)

References