Good News if Certain Diseases Run in Your Family

Health woes common in families may be the result of lifestyle choices you can change, not your genes.

Genes are units of genetic information, stored in each cell of every living being. They determine if you have blue or brown eyes, are tall or short and, sometimes, if you’re likely to develop a disease due to a mutation in a gene inherited from one or both of your parents. Cystic fibrosis and muscular dystrophy are examples of serious diseases known to be inherited. 

But it turns out that some assumptions about the genetic risks of many other serious and far more common diseases that run in families were wrong. And a study conducted by scientists at the University of Edinburgh's Roslin Institute and MRC Human Genetics Unit could help relieve the worries of countless people who feel doomed they’ll develop depression, heart disease, or high blood pressure eventually because so many of their relatives have suffered from these health problems.

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The researchers examined medical information collected from half a million people via the UK Biobank, an international project helping scientists search for the causes of cancer, heart disease, stroke, diabetes, arthritis, osteoporosis, eye disorders, depression, and dementia. The UK Biobank is a repository of blood, urine, and saliva samples collected from volunteers who also have provided information about themselves and agreed to have their health followed.

In addition to studying information compiled on the UK Biobank research subjects, the University of Edinburgh team also studied the family medical histories of the volunteers’ adoptive and blood relatives. In all, the scientists investigated records on 1,555,906 United Kingdom (UK) residents to document the risk of inheriting common diseases that tend to occur in families across the UK, including high blood pressure, heart disease, and several neurological diseases.

“The huge UK Biobank study allowed us to obtain very precise estimates of the role of genetics in these important diseases,” said lead researcher Chris Hayley, PhD, of the University of Edinburgh's Roslin Institute and MRC Human Genetics Unit. 

Although previous studies have identified genes linked with susceptibility to certain medical conditions, genetic factors only account for part of a person's likelihood of developing a disease. The Scottish researchers concluded what’s known as the “heritability” of many diseases passed down through genes has been overestimated by about 50 percent, and the actual cause of health problems that pop up repeatedly in families is often due to personal choices and how people live. These findings should help doctors and patients have a more realistic understanding of the value of genetic testing for identifying people at risk of diseases, they noted.

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Hayley and colleagues found high blood pressure, depression, and heart disease that run in families were primarily linked to relatives sharing the same lifestyles, diets, and living environments — and not caused by inherited genes. However, the family environment and lifestyle appear to play a more limited, or none of importance, in Parkinson’s disease and dementia.

The results of the study underline the need to identify and modify environmental and lifestyle factors that contribute to the development of specific diseases, the researchers concluded. 

The National Institutes of Health (NIH) agrees genes should not be over-emphasized as the cause of diseases that run in families, because lifestyle habits and environment can play a major part in raising or lowering your risk for so many of these health problems. Diet, weight, physical activity, tobacco and alcohol use, occupation, and where you live can all increase or decrease the odds you will develop a specific disease, according to the NIH.

In fact, if your family has a health history of certain medical problems, you may have the most to gain from adopting a healthier lifestyle to reduce your risk for diseases that run in your family, the Centers for Disease Control and Prevention (CDC) notes. Screening tests, such as blood glucose tests for diabetes, mammograms, and colonoscopies when indicated, can find early signs of many diseases and, along with a healthy lifestyle, help you avoid many health problems that other family members have experienced. For more information, visit the CDC’s Family History and Chronic Disease page.