Multifactorial traits

Elston R. The genetic dissection of multifactorial traits. Clinical and Experimental Allergy 1995 2 103-106. 

Table 7-5. The dominant, X-linked, recessive, and chromosomal classes cure assumed to have a mutation component of 1. (Actually, the value is somewhat less if environmentally caused or multifactorial diseases are mistakenly classified in these categories.) The mutation component for congenital malformation and other multifactorial traits is taken as 0.10. The basis for this was explained earlier by the data in Table 7-2.

The normal incidences are taken to be those of the UNSCEAR column in Table 7-5. The mutation component is taken to be 0.1 for congenital malformations and other multifactorial conditions and 1 for the other categories. The mean persistence times are taken as 4 for dominant and X-linked, 100 for recessives, 1.25 for chromosomal, and 10 for congenital anomalies and multifactorial traits. The normal frequency is 10.5 per 100 live births. The contribution from dominant, X-linked, and cytogenetic disorders is hatched. Because recessive diseases make almost no contribution, the white areas are mainly congenital malformations and other multifactorial conditions. 

After about 10 generations, the dominant and X-linked components are largely finished, and the main contribution is from congenital anomalies and multifactorial traits. 

Isolated cleft lip and palate is a multifactorial trait. The recurrence risk of isolated cleft lip and palate is... 

Many disorders that present in adult life, such as coronary artery disease and hypertension, are multifactorial traits. A multifactorial trait results from... 

Taken as a whole, these observations show that parasite lines differ in an immune-dependent manner in their infection/expulsion kinetics. Furthermore, there is heritable variation in survival and fecundity in previously exposed hosts and quantitative variation in the immune response that selected parasite lines elicit. Again, taken as a whole, these observations have the necessary corollary that variation in these traits exists not only in laboratory-maintained isolates but also in helminth species in nature. The phenotypes under consideration here (infection/expulsion kinetics, survival, fecundity) are multifactorial life-history traits. Understanding the basis of variation in the components and interplay of these complex, immune-responsive phenotypes must be of crucial relevance to understanding the immunology of infections of parasitic nematodes. This is of particular relevance in view of current attempts to develop immunological methods of nematode control. 

Quality is a multifactorial concept that includes a large number of factors which have to be taken into account and which are heterogeneous in outcome and in the perception of stakeholders and consumers. Currently, there is huge inconsistency between expectations and reality in relation to the level of different pork quality traits and the uniformity of products from different production systems. 

The term multifactorial refers to the fact that most common diseases are caused by multiple factors their expression is influenced simultaneously by multiple genes (i.e., a polygenic component) and by environmental factors. Because multiple factors are involved in the causation of these traits, they tend to foUow a normal ( bell-shaped ) distribution. An example would be the distribution of diastolic blood pressures in a population (Fig II-5-1). Other traits that have multiple genetic and environmental components include height, we t, and IQ. 

Many disease traits are either present or absent in the individual (e.g., cleft lip and/or palate, club foot, congenital heart defects, cancer, diabetes). These traits are also thought to correspond to the multifectorial model, but the distribution here refers to an underlying liability to develop disease. Expression of the disease occurs only when a specific threshold is reached (Fig H-5 2). For some multifactorial diseases, the threshold differs in males and females. 

Escape Shorter crop growth period and/or early ripening to be able to avoid the critical infestation period, or to have enough yield before the infestation becomes too severe (potato/late blight onion/downy mildew carrot/carrot fly) One or more monofactorial and multifactorial, durable resistance traits against pest and disease affecting yield and/or quality (scab/apple, late blight/potato, lettuce/downy mildew, yellow and brown leaf rust/wheat) weed competition by an allelochemical ability... 

Houle Yes. If it s multifactorial, it s all relative, so that a good allele could well occur in a low IQ person. One of the results that some claim on the basis of quantitative trait loci studies is that if you look at their effects, they re extremely context dependent. That is, if you put the same marker in a different background, you get an extremely different expression of that gene. Unfortunately, there are statistical issues here which I don t think have been worked out. 

The nature and amount of hpids in the diet may not be the only causative factors, however. Heart disease is multifactorial and other risk factors of environment and life style as well as genetically inherited traits, may exert an even greater influence than diet, and these include stress, hypertension, obesity, and lack of exercise. Factors that interact to cause high blood pressure, hypertension, and blood toxins are aU implicated in the development of heart diseases. 

Asthma is a complex multifactorial disease in which allergic sensitization plays an essential role. Sensitivity to indoor allergens is associated with prevalence, severity, and exacerbations of asthma, while exposure to outdoor allergens initiates exacerbations (1,2). A trait for an elevated level of serum IgE is coinherited with bronchial hyperresponsiveness. Thus, there is a second link between IgE and airway inflammation that appears to be independent of specific allergic susceptibility (3). 

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