In the human body, high levels of triglycerides in the bloodstream have been linked to atherosclerosis, and, by extension, the risk of heart disease and stroke.
Apolipoprotein A-V is a recently discovered lipid-binding protein that likely plays an important role in metabolizing triglycerides.
In the study, researchers found that all 11 subjects who carried both copies of this rare variant showed an extremely high and dangerous triglyceride levels in their blood.
According to some population studies with groups in China and Taiwan, a polymorphism in the APOA5 gene (553 G>T shift) is linked with elevated plasma TG levels, which like cholesterol, increase the risk of heart disease.
In order to get a detailed understanding of this potentially important gene polymorphism, Clive Pullinger and colleagues examined the frequency and impact of this variant in a population of Chinese-Americans, as well as four other Asian-American populations (Japanese, Korean, Southeast Asian, and Pacific Islander).
After examining 541 individuals, the researchers found that 15.1 percent of Chinese-Americans with high plasma TG carried at least one copy of the 553T variant, compared with only 3.7 percent of those with normal TG levels; in non-Chinese Asians these values were 13.7 percent and 5.4 percent.
When calculated, the 553T variant corresponds to a 4.4 and 2.5 times greater risk of elevated TG in Chinese-Americans and other Asians, respectively.
In fact, the frequency became even more prevalent at higher levels; 60 percent of individuals with TG of >500 mg/dl carried the variant, and at 1000 mg/dl the frequency rose to 80 percent. And the 11 subjects who had the variant in both copies of their APOA5 gene had an average TG concentration of over 2000 mg/dl, which can pose serious health risks.
However, this specific genetic change seems restricted to Asians, as the researchers studied 779 non-Asian subjects and found only 3 incidences of the 553T variant (2 Caucasian and 1 Hispanic).
The study speared in the August issue of Journal of Lipid Research.