Genetic and Environmental Factors

Rossier BC, Pradervand S, Schild L et al (2002) Epithelial sodium channel and the control of sodium balance interaction between genetic and environmental factors. Annu Rev Physiol 64 877-897... 

Asthma results from a complex interaction of genetic and environmental factors however, the underlying cause is not well understood. There appears to be an inheritable component, as the presence of asthma in a parent is a strong risk factor for the development of asthma in a child. This risk increases when a family history of atopy is also present.13 Approximately 50% of asthma can be attributed to atopy, and atopic asthma is more common in children than adults.3 Furthermore, atopy in childhood asthma is the strongest prognostic factor for continued asthma as an adult.1,3... 

Describe the pathophysiology including genetic and environmental factors that may be... 

Table 11.2. Percentage contribution of genetic and environmental factors to six phenotypes.

Twin, family and adoption studies have provided compelling evidence that there is genetic as well as environmental risk for developing alcoholism. Genetic and environmental factors contribute approximately equal proportions to risk in both men and women [1],... 

Overweight and obesity are caused by a combination of genetic and environmental factors. Some people have a genetic predisposition to gain weight and store fat. For others, the factors that lead to obesity can be found in the world they inhabit and the behaviors they choose. 

Both genetic and nongenetic factors play roles in the transmission of mood disorders. The familial nature of mood disorders is well established. Studies over the past 20 years have consistently documented higher rates of mood disorder in the relatives of individuals with major depression and bipolar disorder than in relatives of healthy controls [6,7], The familial aggregation of mood disorders is the outcome of both genetic and environmental factors. 

The development of autoimmune disease depends on a combination of genetic and environmental factors (Figure 24.1).3-5-28 Most autoimmune diseases are thought to be polygenic, involving more than one gene, and depend on the accretion of a number of genetic traits.5-10... 

FIGURE 24.1 The development of autoimmune disease depends on a combination of genetic and environmental factors. 

Throughout the workshop discussion, as well as in scientific and nonscientific literature, the terms ethnicity and race are often used interchangeably. There are sensitivities surrounding these terms, and trying to get consensus on the definitions was beyond the scope of the workshop. It was recognized that both risk for disease and desirable and undesirable drug responses are variable across the human species, and the variability is dependent on both genetic and environmental factors, many of which may differ between populations. 

Akerblom, H.K., Knip, M., Hyoty, H., Rejijonen, H., Virtanen, S., Savilahti, E. and Ilonen, J. (1997). Interaction of genetic and environmental factors in the pathogenesis of insulin-dependent diabetes mellitus, Clinica Chimica Acta, 257, 143-156. 

In humans, there is considerable interindividual variation in the rate, extent, and pattern of nicotine metabolism in vitro (Messina et al. 1997) and in vivo (Benowitz et al. 1994). Such variation can arise from both genetic and environmental factors. Twin studies allow an estimate of the relative contribution of heritability (i.e., contribution of genes) and environmental influences to a particular phenotype. An investigation in twins of primarily Caucasian ethnicity found that 59% of the variance in nicotine clearance can be attributed to genetic influences (Swan et al. 2005). 

Cardiovascular and cerebrovascular disorders associated with lipid metabolism disturbance and atherosclerosis represent major risk factors for dementia (3,25,59). Atherosclerosis is the primary cause of heart disease and stroke in which genetic and environmental factors converge (553). More than 90% of patients older than 70-80 yr with dementia show signs of atherosclerosis in their arteries and a clear cerebrovascular component in their dementia process. It is very likely that pure AD is practically absent in octogenarians, in whom the prevalent diagnosis is vascular or mixed dementia (3,25,59), in which the APOE-4 allele also accumulates (18-20,554). 

A particular disorder might be described as "running in a family" if more than one person in the family has the condition. Some disorders that affect multiple family members are caused by gene mutations, which can be inherited (passed down from parent to child). Other conditions that appear to run in families are not inherited. Instead, environmental factors such as dietary habits or a combination of genetic and environmental factors are responsible for these disorders. 

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