What are complex or multifactorial genetic disorders?

Samuel M. Warren, MD

Don't get too caught up in the terminology.  Most all common medical conditions arise from the interaction between multiple genes and multiple non-genetic factors, and are thus “multifactorial genetic conditions”. 

Among the common chronic diseases that are more likely to kill you before you feel ready to die – such as cardiovascular disease, diabetes, and cancer - it is widely accepted that the non-genetic factors have greater influence on your risk than do the genetic factors.  This is good news, since many of those non-genetic factors are things you have control over. 

Here is some high-quality science to back that up:

*38% of U.S. deaths are attributable to the following habits: tobacco, poor diet, physical inactivity, and problem drinking (Mokdad AH et al. JAMA 2004; 291:1238). 

*30% of healthy life years lost in the U.S. are attributable to the following risk factors: tobacco, alcohol, overweight, high blood pressure, elevated serum lipids, low fruit and vegetable consumption, and physical inactivity (Murray CJ et al. Am J Prev Med 2005; 29(5 Suppl 1):4).

Genomic science is progressing rapidly and genetic knowledge in some cases will help empower patients who want to better predict their disease susceptibilities.  

Unless, that is, we undervalue non-genetic factors in the process.      

Genetic disorders that have several causes - not mutations in just one gene - are called complex or multifactorial disorders. Cancer, heart disease, and Alzheimer's disease are examples of this type of disorder. Their causes are very complex and include some changes in genes but environmental and lifestyle factors as well. There is some grouping of these diseases in families but no definite inheritance patterns exist at this time.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.