Family Health History: An Entry for Personalized Medical Practice in Primary Care

Generally, actual risk assessment algorithms derived from FHH information vary for different diseases, especially when other factors, such as age of onset, severity, recurrence, and environmental risk factors are known to be involved. For some diseases, FHH-based risk is described primarily for first degree relatives. In such cases, individual risk is elevated substantially if an immediate (first degree) family member is affected, and the additional risk revealed by affected second degree relatives may not be necessary for generating additional recommendations, and/or treatment interventions, though this information could be valuable if a genetic test is contemplated. 

For assessing a patient’s risk for developing diabetes mellitus, for example, having a first degree relative with type 2 diabetes significantly elevates personal risk (~2-5 fold), even without knowing exacerbating environmental risk factors and without information from more distant relatives. While specific genetic variants (any structural change in the nucleotide sequence of DNA will be referred to as a variant in this mini review) that occur commonly in the human population have been associated with a risk for type 2 diabetes, FHH remains a more robust predictor of T2D risk than the presence of predisposing genetic variants. For stroke, FHH is a well-established risk factor.

 According to one study, over 85% of strokes in persons less than 75 years old are concentrated in about 10% of all families, suggesting the risk-elevating effects of genetics and shared family environment. If one or both parents of a patient had a stroke, a patient’s risk for stroke or cardiovascular disease is significantly increased. Such information offers a simple and effective form of triage for evaluating a patient’s risk for stroke as well as possible interventions, including aggressive treatment of even modest hypertensive levels, which has been shown to reduce the risk of cardiovascular disease and stroke by one-fourth to one-third.

Several genetic associations have been tentatively made for a variety of specific types of stroke, precluding the utility of a simple genetic test for stroke risk [10]; the disease itself is heterogeneous in terms of cause and type, and these subtypes involve a variety of potential variants, none of which have been validated as predictors of stroke risk in the general population. As the relationship between specific types of stroke and predisposing genetic and environmental factors becomes more defined however, it is plausible that more precise diagnoses, preventive interventions, and treatments will be forthcoming.