What is the Cause of Fragile X Syndrome?

People often ask, "Why us? Why does our family have to deal with the challenge of fragile X syndrome?" The larger question of "Why?" must be left for the fields of philosophy and theology. However, science has begun to explain the role of molecules in triggering fragile X syndrome.

Used with permission of Paul Thiessen Chemical Graphics

What is the biological cause of fragile X syndrome? There are several ways we can answer that question. 

1. We could focus on the molecules that play a role in fragile X. The immediate cause is that a person with fragile X syndrome does not make a specific protein, FMRP (fragile X mental retardation protein). This absence sets in motion the various characteristics of fragile X syndrome.

2. We could focus on the brain, where many of the impacts of fragile X occur, . Research on the anatomy of the brain may help us understand the changes that occur when there is reduced FMRP production.

3. We could focus on the inheritance of fragile X syndrome by looking at how the gene that causes fragile X (FMR1) was transmitted by the grandparents and parents. 

4. We could also go back farther in history to try to understand why fragile X syndrome develops in certain families or populations but is less likely to appear in others.

5. We could look at studies done in the knockout mouse for clues about the cause of fragile X syndrome.

What is the molecular cause of fragile X syndrome?

How do changes in brain anatomy cause fragile X syndrome?

How is fragile X syndrome inherited?

Why does fragile X syndrome appear in some families and not others?

What have we learned from the knockout mouse?

For a review of molecular studies, see:
O'Donnell, WT, Warren ST. 2002. A decade of molecular studies of fragile X syndrome. Annu. Rev. Neurosci 25:315-38

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This page last updated Saturday, November 04, 2006