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Variant of the angiotensin II type 2 receptor gene alters heart structure
By Sharon Guynup

A team of German researchers has linked a genetic mutation in the angiotensin II type 2-receptor (AT2-R) gene with structural changes in the heart, according to a new study.

Roland E. Schmieder, of the University of Erlangen-Nürnberg, and colleagues found that a frequently occurring X-chromosome polymorphism of the AT2-R gene is linked to thickening of the walls and the general mass of the heart's left ventricle.

The researchers compared genomic DNA with the echocardiograms of two groups of young white males—one group with normal blood pressure and the other with mildly elevated readings. All of the men carrying the A-allele of the AT2-R gene—57 percent—had thicker left ventricular walls and greater left ventricular mass than those carrying the G-allele.

During the past five years, researchers have associated various genes of the renin angiotensin system with heart disease. When the body senses a drop in blood pressure, this system initiates a chain reaction of chemical responses, which ultimately produces angiotensin-II, constricting blood vessels and raising blood pressure.

The AT2-R gene has a range of functions. It decreases blood pressure, controls proliferation of some heart, blood, and lymph cells, and modifies growth in the left ventricle. Enlargement of the left ventricle significantly raises the risk of developing arterial hypertension and suffering a fatal heart attack.

But it is not yet clear whether the polymorphism affects gene function or expression, or works in concert with yet unknown polymorphisms in neighboring genes.

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Schmieder, R.E. et al. Effect of the angiotensin II type 2-receptor gene (+1675 G/A) on left ventricular structure in humans. J Am Coll Cardiol 37, 175-182 (January 2001).

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