The human body consists of cells. These cells contain a nucleus with the DNA. The DNA contains all the information that an organism uses to function.

The DNA is contained within chromosomes. Humans have 46 chromosomes. Each chromosome contains the DNA for many genes.

In myotonic dystrophy there is an abnormally expanded stretch of DNA in the myotonic dystrophy protein kinase (DMPK) gene at chromosome 19.

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