New experiments in mice have uncovered a gene that can increase cholesterol levels.And a second study has confirmed that your cholesterol reading can change with the seasons.In the first study, a newly discovered gene was found to play a large role in the levels of low-density lipoprotein (LDL) cholesterol, a fatty molecule that contributes to hardening of the arteries.Kara Maxwell, an M.D.-Ph.D. student at Rockefeller University in New York City, and her colleague, Dr. Jan L. Breslow, found that a gene called Pcsk9 reduces the number of receptors on liver cells that remove LDL cholesterol from the blood."It appears that when you have too much of Pcsk9, it causes decreased LDL receptor protein and function,” Maxwell said. “This leads to high levels of LDL cholesterol in the blood."Maxwell and Breslow fed one group of mice normal diets and another group high-cholesterol diets. They then examined the gene activity in the mice and found a previously unknown gene.This gene was seen at much lower levels among mice on the high-cholesterol diet, compared with mice fed normal the diet.
