High-density lipoprotein (HDL) cholesterol helps carry damaging substances away from the walls of the arteries, earning for it the reputation as the "good cholesterol." However, a gene mutation can cause HDL to go over to the dark side, a study found.

Researchers found that individuals with a faulty SCARB1 gene have high levels of the "good" HDL cholesterol. However, they also have an 80 percent increased risk for heart disease when compared to individuals without the gene mutation.

The international team of scientists analyzed the DNA of 328 participants who had high HDL levels in the blood. They compared the data to the DNA of individuals with low levels of HDL (control group). They focused on the gene SCARB1, which is an encoder for the Scavenger Receptor B1 (SR-B1), a major HDL receptor on cell surfaces.

They found that there are individuals who lacked SCARB1 function, which is demonstrated by a very high level of HDL - approximately 150 mg/dL - compared to the normal 50 mg/dL. These individuals had duplicates of the P376L - the SCARB1 mutation. The researchers showed that the gene mutation causes the HDL receptor's function breakdown.

"This mutation prevents the receptor from getting to the cell surface where it needs to be situated in order to bind and take up HDL," said senior study author Dr. Daniel J. Rader, the genetics department chair at the University of Pennsylvania's Perelman School of Medicine. The research was the first one to demonstrate how a gene mutation can increase the levels of HDL and heart disease risk.

In the United Kingdom, coronary heart disease accounts for more than 73,000 deaths annually. According to the National Health Service, approximately one in six men and one in 10 women die from coronary heart disease.

There are about 2.3 million patients suffering from the heart condition. Additionally, there are about 2 million people suffering from angina, which is the condition's most common symptom. Angina is a type of chest pain linked to restricted blood supply to the heart's muscles.

"This discovery could lead to new drugs that improve the processing of HDL-C to prevent devastating heart attacks," said Dr. Adam Butterworth from the Cardiovascular Epidemiology Unit at the Cambridge University.

Photo: Alden Chadwick | Flickr