Daily Archives: 22 March, 2012

Heart disease may be passed on through DNA

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Coronary artery disease, which kills tens of thousands each year, may be passed genetically from father to son, according to a new study.

The study, led by the University of Leicester, shows that the Y chromosome – a part of DNA only present in men – plays a role in the inheritance of the disease.

Coronary artery disease involves the narrowing of blood vessels delivering blood to the heart, and can lead to angina symptoms, such as constriction of the chest, and heart attacks. Scientists analysed DNA from over 3,000 men enrolled in a heart health study and found that 90 per cent of British Y chromosomes belong to one of two major groups.

The risk of coronary artery disease among men who carry a Y chromosome in one of the two groups is 50 per cent higher than for other men, and is independent of traditional risk factors such as high cholesterol, high blood pressure and smoking. The researchers believe the increased risk is down to the specific group’s influence on the immune system and inflammation.

Arteries

Arteries

Principal investigator Dr Maciej Tomaszewski said: “We are very excited about these findings as they put the Y chromosome on the map of genetic susceptibility to coronary artery disease. We wish to further analyse the human Y chromosome to find specific genes and variants that drive this association. “The major novelty of these findings is that the human Y chromosome appears to play a role in the cardiovascular system beyond its traditionally perceived determination of male sex.


Dr Hélène Wilson, research advisor at the British Heart Foundation (BHF), which was the main funder of the study, said: “Lifestyle choices such as poor diet and smoking are major causes, but inherited factors carried in DNA are also part of the picture.

“The next step is to identify specifically which genes are responsible and how they might increase heart attack risk.”

“This discovery could help lead to new treatments for heart disease in men, or tests that could tell men if they are at particularly high risk of a heart attack.

High fat diet linked to breast cancer

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Breast cancer rates are five times higher in Western countries than in other developed countries, and studies have shown that rates increase in immigrant communities who come from low-incidence areas. This has suggested to scientists that environmental factors play a high part in the progress of the disease.

Now a group of researchers from Jefferson University in the US has found that mice fed a western-style diet high in fat and cholesterol are more likely to develop breast cancer than mice placed on a control diet, and that breast cancer tumours are larger and grow faster.

Dietary fat and cholesterol have been shown to be important risk factors in the development and progression of a number of tumour types, but diet-based studies in humans have reached contradictory conclusions. This is why the scientists considered a mice-based study.

The mice were of a type believed to closely parallel the course of human breast cancer. One set were placed on a diet that contained 21.2 percent fat and 0.2 percent cholesterol, reflective of a typical Western diet, and another on a diet with 4.5 percent fat and negligible amounts of cholesterol.

The researchers found that tumours began to develop quickly in mice fed the fat/cholesterol-enriched food. In this group, the number of tumours was almost doubled, and they were 50 percent larger than those observed in mice that ate a normal diet.

breast-cancer-cell

Breast cancer cell

Commenting on the results, study leader Philippe G. Frank said: “The consumption of a Western diet resulted in accelerated tumour onset and increased tumour incidences, multiplicity, and burden, suggesting an important role for dietary cholesterol in tumour formation.”


He also noted that there was an increase in lung tumours in the mice fed the high fat diet.

The study noted that cholesterol levels dropped in those mice that developed the tumours. This suggests that the cholesterol is actually fuelling the development of the tumours. Thus an otherwise unexplained drop in blood cholesterol levels may provide a useful indicator of the development of cancer tumours.

The research team also discovered the same association between cholesterol and growth of prostate cancer in mice in a study published in the December issue of The American Journal of Pathology, as was the new study.

The results of these two new studies indicate, according to Dr. Frank, that “cholesterol does indeed seem to be an important factor in the regulation of tumour formation in several cancer types.”