New Delhi: Higher Apolipoprotein B or apoB shortens lifespan, increases risk of heart disease and stroke, and in multivariable genetic analyses that account for LDL cholesterol, increases risk of diabetes, a new study has found. The study conducted by researchers at University of Bristol and University of Oxford was published in the medical journal The Lancet Friday.
Apolipoproteins are proteins that bind to lipids to form lipoproteins, whose main function is to transport lipids or fats to all cells in the body. There are six major classes of apolipoproteins: A, B, C, D, E and H. ApoB is the main apolipoprotein of both chylomicrons and low-density lipoproteins (LDLs) commonly and wrongly known as “bad cholesterol”.
It is produced by the small intestine and the liver. High levels appear to be associated with a genetic risk of heart disease, although their mechanism of action and effect on the body is not fully understood yet and is the subject of ongoing, intense research.
While the role of apoB in coronary heart disease is becoming increasingly clear, it is still not clear what role apoB and LDLs play in other diseases, including ones that shorten lifespan.
How the study was conducted
The participants were asked whether their father, mother, or siblings had any of the following diseases: heart disease, stroke, high blood pressure, chronic bronchitis or emphysema, Alzheimer’s disease or dementia, diabetes, Parkinson’s disease, severe depression, lung cancer, bowel cancer, prostate cancer, or breast cancer. Additionally, individuals were asked whether their mother and father were still alive, and if not, at what age they had died. The study said that it used this information to evaluate the effects of genetically predicted apoB on outcomes in first-degree relatives.
“Our evaluation of apoB using outcomes in first-degree relatives identified that higher apoB is detrimental to lifespan and increases the risk of coronary heart disease and type 2 diabetes. Lifestyle and pharmacological approaches to lowering apoB should have widespread beneficial effects, including preventing common diseases and prolonging life,” the study said.
The study was conducted using data from the UK Biobank, the world’s largest, long-term study into the role of genetics and environment in development of a disease. UK Biobank comprises approximately 5,00,000 participants who were recruited between 2006 and 2010 from 22 assessment centres across the UK.
The association between apoB and the diseases was then compared with previously published results, and was consistent. The authors also replicated the findings for lifespan and type 2 diabetes by performing a genome-wide association study (GWAS), where the entire DNA of an individual is sequenced and genetic variants or mutations are identified that are associated with certain traits.
What the study found
The study concluded that it is apoB that contributes to formation of fatty acid deposits on arteries which manifests in the form of heart disease.
The study found that apoB had “a deleterious effect on longevity, shortening the lifespan by a period of months to years. Furthermore, apoB caused higher risks of coronary heart disease and stroke in first-degree relatives. Finally, apoB was identified to increase the risk of type 2 diabetes.”
It also said that genetically elevated apoB was associated with lower odds that an individual’s parents were alive. A higher risk of heart disease was evident in all first-degree relatives of individuals with genetically elevated apoB. Mothers of individuals with genetically elevated apoB had a higher risk of stroke. Parents of individuals with genetically elevated apoB had a lower risk of type 2 diabetes.
The findings of the study implicate apoB in several major diseases, including heart disease, stroke, and diabetes. Importantly, a higher apoB was associated with a shorter lifespan in parents. These findings have important implications for the treatment of cardiovascular and other lifestyle diseases.
“Taken together, our findings show that reductions in apoB should be the primary goal of lipid lowering, because not only does this lead to lower risk of common diseases such as heart disease and stroke, but also a reduction in apoB prolongs life by a period of months to years,” the study said.