Flawed Stem Cells Yield Fragile X Clues: Researchers study genetic disorder via discarded embryos

Science News ^ | Week of Nov. 17, 2007 | Brian Vastag

[neverdem]

Scrutinizing the first days of development in abnormal embryonic stem cells, researchers have uncovered a basic mechanism underlying fragile X syndrome, the most common inherited cause of mental retardation in boys.

"It could have important implications for treatment," says W. Ted Brown, cochair of the scientific committee of the National Fragile X Foundation, which helped fund the work.

The research also highlights the value of embryonic stem cells for studying genetic diseases, says Yang Xu, a stem cell researcher at the University of California, San Diego.

Fragile X syndrome is caused by a mutation in a gene called fmr1. By stopping the gene from making its protein, the mutation leads to learning disabilities, elongated facial features, speech and language difficulties, emotional problems, and other symptoms. In boys, who have only one copy of the X chromosome, a single...

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Despite carrying the fragile X mutation, the embryonic cells unexpectedly produced the fmr1 protein. "We were extremely surprised," says Benvenisty. But when the team prodded the cells to begin developing into a range of tissues, the gene promptly shut down. "The [mutation] itself is not sufficient for the gene silencing," says Benvenisty. "Something happens during development."

Delving further, the team determined that changes in the gene's wrapper, a structure called chromatin, switched off the gene. Those changes occur only after cells grow out of their embryonic state, presenting a window of opportunity for drug therapy, says Benvenisty. In addition, chromatin is easier to modify than the gene itself. His team is now screening drugs that might prevent the gene silencing by fixing the chromatin.

Other teams have created stem cells from embryos carrying genetic diseases, but Xu says that this is the first time the method has yielded a fundamental disease discovery. The study appears in the November Cell Stem Cell.

[neverdem]

Developmental Study of Fragile X Syndrome Using Human Embryonic Stem Cells Derived from Preimplantation Genetically Diagnosed Embryos

If the authors are correct, there is no other way to do this research.

[TenthAmendmentChampion]

Ping

[neverdem]

Since they were destined to be destroyed, at least they gained some understanding of the epigenetics of Fragile X syndrome.

[Dr. Scarpetta]

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