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Types of Mutations

Types of Mutations

Chromosomes are like chapters in a book and our genes are the sentences in our book.

Mutations are like a misspelled word or a disruption in one of those sentences. There are various types of mutations responsible for the symptoms of Duchenne.

Below describes what different types of mutations would look like if the DMD gene where sentences in a book:

Image depicting the analogy of a book representing DNA, a chapter representing a chromosome and a sentence representing a gene

Imagine the above sentence “THE CAR WAS RED” was the DMD gene of an individual without Duchenne. The different mutations of Duchenne would look like the following:

Deletion Mutation: THE ___ WAS RED. (subtracting a word) or THE _AR WAS RED. (subtracting a letter)

Insertion/Duplication MutationTHE CAR WAS RED RED. (add one word) or THE CAR WAS ERED. (add one letter)

Missense Mutation: THE CAR WAS HAT. (changed one word) or THE CAR WAS RDD. (changed one letter)

Nonsense MutationTHE CAR. (ends the instructions too soon)

The DMD gene is constructed like our example of sentences shown above. However, each three-letter word is an exon. The DMD gene is very large and contains 79 exons or 79 three letter words. Below is a picture of the DMD gene with all 79 exons perfectly fitting together like a puzzle.

Image depicting exons as puzzle pieces numbered one through seventy-nine

Understanding which type of mutation is responsible for your child’s diagnosis of Duchenne can enhance your treatment journey.

Some treatments, such as exon skipping therapies, are based on the specific genetic change your child may have. Therefore, it’s important you know what your mutation is, as it may determine your eligibility for a clinical trial and/or future access to a treatment once approved in Canada.

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