DMD/BMD

Duchene and Becker muscular dystrophies (DMD/BMD) are genetic conditions that affect skeletal and heart muscles. DMD/BMD almost exclusively affect males.

Genetic Cause:

Males are affected more than females because DMD/BMD is an X-linked condition. This means that the DMD/BMD gene is on the X chromosome, and females have two X chromosomes (XX), and males have one X and one Y (XY). Thus, females have a “backup” DMD/BMD gene on the other X chromosome that can compensate for the DMD/BMD gene that is not working on the other. But, since males have only one DMD/BMD gene, if that one is not working, then there is no backup.

Changes in the same gene cause DMD/BMD, but DMD is generally more severe than BMD and begins earlier in life. The gene makes a protein called dystrophin which is made in the skeletal and heart muscles and protects the muscles from damage. So, when the gene is making a protein that is not working correctly, it leads to muscle damage that causes the signs of DMD/BMD.

The general signs include delayed sitting, standing, and walking as a child. Most boys with DMD/BMD need a wheelchair before their 20s.

Since the heart is also affected, these signs can include irregular heartbeats, shortness of breath, tiredness and swelling of the legs and feet. This can become life-threatening and is one of the main reasons for the reduced lifespan of those affected by DMD/BMD.

Males with DMD generally live into their 20s and BMD males into their 40s.

Treatment:

Sadly, there is no cure for DMD/BMD, but there is ongoing gene editing and medication research to try to alleviate the condition. Recently, scientists have been using CRISPR as a therapy to treat DMD/BMD. They are currently using animal models and human cells but are hopeful to move to clinical trials soon!

You can read more about CRISPR therapy at https://utswmed.org/.../duchenne-muscular-dystrophy.../.

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