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Permalink Reply by Brian Denger on July 25, 2008 at 7:25am

Erin,

I am sorry to read what you are going through and how this is troubling you. First, Duchenne and Becker are names attributed to this single gene disorder based on variations of the genotype (The genetic make up) and phenotype (Physical characteristics). There are mutation types that indicate the likelihood an individual may present with Duchenne or Becker, yet even then there are differences within the community and in families.

My two sons were diagnosed with Duchenne and have the same deletion type. My older son had very early symptoms which led us to seek a diagnosis. He stopped walking at age eight and now at sixteen has limited upper body strength. My younger son stopped walking independently after he turned thirteen and at fourteen he is able to help us move him small distances when he is fully supported. He also has significantly stronger upper body strength compared to his brother. The difference is partially in body type and also in other genetic circumstances. There are genetic promoters and enhancers that hasten or slow the progression in one or the other.

It may be possible your son will have a much different progression than your brother. I hope things work out and you get the solid answers you seek at your appointment.

Brian Denger

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Permalink Reply by Keith Van Houten on August 18, 2008 at 11:56am

What deletion did the DNA work show he has?

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StaffPermalink Reply by Pat Furlong on August 18, 2008 at 12:48pm

Hello Erin,
It is really difficult to say a great deal at 2 years of age. During this time the boys are gaining skills, making their own modifications and refining their activities. There is also the issue that you now have a diagnosis and you are much more aware of the symptomatology.

Duchenne and Becker are on a spectrum. Duchenne, by definition is 0-,<8 or10% dystrophin. Becker is generally thought to be >10% dystrophin. Another related definition has to do with 'in-frame' vs 'out of frame'. I'm sorry if you have heard this multiple times, but 'in-frame' deletions mean the genetic recipe is still 'readable', still make sense, therefore Dystrophin is produced. If the deletion is 'out of frame", the genetic recipe makes no sense, is unreadable and therefore there is no dystrophin expressed. The bottom line here is IF dystrophin is produced and in what quantity.

In terms of the cardiac problems. We are getting better at this, treating the boys with cardioprotective meds, doing baseline studies (echocardiogram, cardiac mri later perhaps) early on and understanding to some degree genotype/phenotype associations. There are 8 different isoforms of Dystrophin. That means, the 'recipe' for Duchenne has a number of moving parts, using different parts of the 'recipe' to create Dystrophin for other organs and tissues.

With certain mutations, physicians/researchers are able to suggest that (for instance) based on the mutation, the isoform for cardiac dystrophin may be absent or the isoform for brain dystrophin may be absent and in these instances, we might see huge cardiac problems or behaviors such as autism spectrum. We are learning more every day about these issues, again remember that our genes are influenced by other genes as well as external factors.

The diagnosis of Duchenne vs Becker is often difficult to determine as there are categories such as 'mild becker, severe becker, mild duchenne, severe duchenne. It is pretty complex and the bottom line will have to do with how much dystrophin he is producing, if the dystrophin is efficient, genetic modifiers and external influences. All this to say, it is fairly complex and often difficult to predict.

And your question about variability in families. There is often wide variability in families, brothers often progress at very different rates. There are a number of factors that influence this as described, genetic modifiers, other genes that are up-regulated or down-regulated affect muscle degeneration (for better or worse). Add into that external factors such nutrition, environment, overall health.

All of this actually comes down to making sure you find an inter-disciplinary team of physicians that you trust who will evaluate your little boy, evaluate his needs and be proactive about his care.

Erin, I hope I have not confused you. It is just so early because your son is just 2 years old to predict progression. While the mutations will be the same, there are other influences as well.

And finally, the field is moving rapidly (not ever fast enough I realize) and I believe your son will live long and happy. Please let me know how I can be of help (or if I have totally confused you)

Warm regards

Pat Furlong

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Permalink Reply by Jacobs Mommom on August 18, 2008 at 4:16pm

Pat:

Is there a chart that can tell us what mutations have what problems?

With certain mutations, physicians/researchers are able to suggest that (for instance) based on the mutation, the isoform for cardiac dystrophin may be absent or the isoform for brain dystrophin may be absent and in these instances, we might see huge cardiac problems or behaviors such as autism spectrum. We are learning more every day about these issues, again remember that our genes are influenced by other genes as well as external

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