Dystrophinopathies are a group of conditions that generally cause muscle weakness. Duchenne/Becker (DMD/BMD) muscular dystrophies are the most frequent myopathies and are caused by genetic alterations in dystrofin gene (DMD). They are inherited in an X-linked manner, which means that females are far less likely to experience symptoms compared to males. However, up to 20% of females may also experience mild symptoms.
DUCHENNE MUSCULAR DYSTROPHY
Duchenne muscular dystrophy (DMD) is characterized by progressive muscle weakness and degeneration. Symptoms typically begin in early childhood with the first muscles affected being those of the hips, pelvic region, thighs, and shoulders. Muscle weakness of these areas results in general motor (sitting up, standing, walking) delays and an abnormal gait (way of walking). A small percentage of males also develop learning difficulties early in life, though the level of intellectual disability is variable. Because DMD is progressive, most individuals will need a wheelchair by 13 years of age. By the mid-teenage years the heart muscles will weaken (dilated cardiomyopathy), as will the respiratory muscles, which can lead to early death.
BECKER MUSCULAR DYSTROPHY
Becker muscular dystrophy (BMD) is similarly characterized by muscle weakness and dilated cardiomyopathy. However, symptoms are much more variable in presentation, may be milder, and tend to develop later than DMD. In addition, a longer life expectancy is generally seen with BMD in comparison to DMD.
The presence of deletions and duplications in the DMD gene are detected using the MLPA technique. About 75% of pathogenic variants in DMD gene are deletions and duplications, the remaining 25% is caused by point mutations in the same gene.
Sample type: Peripheral blood in EDTA
Time to result: 2 weeks
Upon negative result we can proceed with the analysis of the coding region of DMD gene using Next Generation Sequencing, at an additional cost.
Time to result: 4 weeks