New mechanism causing facioscapulohumeral muscular dystrophy proposed

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Professor Jane Hewitt and colleagues at the University of Nottingham have published the results of an evolutionary study which sheds new light onto the genetic defect leading to facioscapulohumeral muscular dystrophy


  • What is facioscapulohumeral muscular dystrophy (FSH)?
  • What is the genetic cause of the condition?
  • What does the new research entail?
  • In summary, what are the implications for people with FSH?
  • Further information and links

What is facioscapulohumeral muscular dystrophy (FSH)?

FSH is the second most prevalent muscular dystrophy in adults affecting one in 20,000 people in the UK. It is a highly variable type of muscular dystrophy with muscle weakness appearing any time from early infancy to late life but typically in the second decade of life.

What is the genetic cause of the condition?

The condition is caused by a rearrangement in the genome in an area of a highly repetitive nature. It is an unusual segment of DNA that contains many copies of the same sequence and is called D4Z4. In healthy individuals the number of repeats varies between 11-100 copies. People with FSHD have a deletion at this location and the number of copies is reduced to less than 11.

Until now the scientific community had not come to an agreement about the function of these DNA repeats. Some scientists think that D4Z4 regulates the activity of neighbouring genes without being a gene itself, and that a deletion in this area alters the amount of protein these genes normally produce with then leads to FSHD.

What does the new research entail?

Professor Jane Hewitt’s group has now shown that D4Z4 sequences are also present in other mammals, including mice, rats and elephants. The detailed examination of these sequences in other species has revealed that the potential of D4Z4 to produce a protein has been conserved for over 100 million years of evolution. Hence, her findings support the theory that D4Z4 indeed represents a gene which carries the information for a protein. This protein is predicted to regulate the activity of other genes.

Her work has shown that mice have a D4Z4 sequence which means that it may be possible to make a mouse model of FSHD.

An animal model for the disease will enable researchers to study the disease in more detail and to test the potential of possible approaches to treat the condition.

In summary, what are the implications for people with FSHD?

The results of Professor Hewitt’s work have provided new evidence for understanding a possible molecular mechanism causing FSHD. This might be the basis for the future development of therapeutic interventions and treatments.

Further information and links

The paper referred to in the above article was published in the journal American Journal of Human Genetics which is available by subscription only so the original article is not freely available. The article itself is written in technical language with no summary in layman’s terms.

About facioscapulohumeral muscular dystrophy

For more information about this condition, go to our information pages.

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