Genetics and Family History

positive family history increases risk:

A father's premature heart attack doubles the risk of a heart attack in his son, and increases his daughter's risk by 70% (1,2).

One study on CV risk related to parents showed the following:

One parent over 50 years old with a heart attack increases risk 67% (3).

One parent younger than 50 with a heart attack increases risk by 236% (3).

Both parents with heart attacks over 50 increases risk by 290% (3).

Both parents with heart attacks when one was under 50 increases risk by 326% (3).

Both parents with heart attacks when both are under 50 increases risk by 656% (3).

One sibling with CV disease increases the risk of CV disease by 45% (4).

A normal family history can give a false sense of security  

Although a family history of heart disease or strokes is very important, a normal family history can give a false sense of security. Previous generations had more physically demanding jobs, so they were more physically active and less obese. Some genes related to heart disease become activated by gaining weight, and are therefore being expressed more frequently today than in previous generations. Some genes are recessive by nature, meaning that someone can inherit a bad recessive gene from both sides of the family and be that "one in four" sibling who has that bad gene, a gene that may not have been expressed.

Someone who has parents or other family members with early heart attacks or strokes should take an aggressive approach to screening. But someone who has other risk factors but a normal family history should also be screened.

If you were adopted with no access to family history, you should assume the worst. Don't wait to find out you have a problem by having an event.

references:

1. Lloyd-Jones DM, et al. Parental cardiovascular disease as a risk factor for cardiovascular disease in middle-aged adults: a prospective study of parents and offspring. JAMA. 2004;291:2204-2211.
2. Sesso HD et al, Maternal and paternal history of myocardial infarction and risk of cardiovascular disease in men and women. Circulation. 2001;104:393-398
3. Data from Table 7-1, Heart Attack and Stroke Statistics-2015 Update, Chapter 7. Circulation, which derived data from Chow CK et al. Parental history and myocardial infarction risk across the world: the INTERHEART study. J Am Coll Cardiol. 2011;57:619-627
4. Murabito JM, et al. Sibling cardiovascular disease as a risk factor for cardiovascular disease in middle-aged adults. JAMA. 2005;294:3117-3123