Genetic switch key to heart`s health discovered

London: Scientists have discovered a genetic switch that influences the heart`s health, a finding they say offers new insights into the genetic roots of congenital heart disease and could lead to developing new treatments for this potentially fatal disorder.

Scientists from the Gladstone Institute in San Francisco found that a specific gene in mice which fails to turn off at the right time in an embryo`s development could mean illness later in life.

They found that rodents in which the gene was left active were born apparently healthy, but suffered heart muscle problems later.

Prof Peter Weissberg from the British Heart Foundation said the the research was "important" and it might one day be possible to fix the genetic switch.

"What this shows is that a really crucial step in normal heart development is the switching off of genes. If this doesn`t happen, and they continue to be expressed, this can
cause trouble later in life," Prof Weissberg was quoted as saying by the BBC.

For the study, published in the journal Nature Genetics, the scientists focused on two genes and their role in cardiomyopathy, a enlarging and weakening of the heart muscle
which is a feature in life-threatening heart defects in children and adults.

One of the genes, called Six1, appears to play an important role in embryonic heart development, while the other, Ezh2, seems to have the job of switching off genes,
including Six1, when they are no longer needed.

The researchers tested the precise relationship by stopping Ezh2 from working in the embryo and foetus at various points during pregnancy, thereby allowing Six1 to go on
working for longer than usual.

They found that while the mice were born apparently normal and healthy, they then started to develop the signs of cardiomyopathy.

The finding suggested that although leaving Six1 switched on in humans might produce a seemingly healthy baby, it could be storing up heart problems for later in life.

Analysis of the results also revealed that in a healthy pregnancy, Six1 should only normally be switched on briefly during heart development.

Dr Paul Delgado-Olguin, one of the team, said: "When Six1 remains active for too long in Ezh2-deficient mice, it boosts the activity of other genes that shouldn`t be activated in
heart muscle cells - such as genes that make skeletal muscle.

"The enlargement and thickening of the mice`s hearts over time eventually led to heart failure."

The researchers hope that further work will reveal more about the roots of congenital heart problems in early life.

Prof Weissberg said that there was the possibility that faulty gene expression could be corrected, although it would be some years before such techniques could be used in humans.

The possible reasons for the faulty "switch" – whether dietary, medical or something else -- could also be investigated, he added.


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