Genetic predisposition

A genetic predisposition is a genetic characteristic which influences the possible phenotypic development of an individual organism within a species or population under the influence of environmental conditions. In medicine, genetic susceptibility to a disease refers to a genetic predisposition to a health problem, which may eventually be triggered by particular environmental or lifestyle factors, such as tobacco smoking or diet. Genetic testing is able to identify individuals who are genetically predisposed to certain diseases.

Behavior

Predisposition is the capacity humans are born with to learn things such as language and concept of self. Negative environmental influences may block the predisposition (ability) one has to do some things. Behaviors displayed by animals can be influenced by genetic predispositions. Genetic predisposition towards certain human behaviors is scientifically investigated by attempts to identify patterns of human behavior that seem to be invariant over long periods of time and in very different cultures.

For example, philosopher Daniel Dennett has proposed that humans are genetically predisposed to have a theory of mind because there has been evolutionary selection for the human ability to adopt the intentional stance.^[1] The intentional stance is a useful behavioral strategy by which humans assume that others have minds like their own. This assumption allows one to predict the behavior of others based on personal knowledge.

In 1951, Hans Eysenck and Donald Prell published an experiment in which identical (monozygotic) and fraternal (dizygotic) twins, ages 11 and 12, were tested for neuroticism. It is described in detail in an article published in the Journal of Mental Science in which Eysenck and Prell concluded that, "The factor of neuroticism is not a statistical artifact, but constitutes a biological unit which is inherited as a whole....neurotic Genetic predisposition is to a large extent hereditarily determined."

E. O. Wilson's book on sociobiology and his book Consilience discuss the idea of genetic predisposition of behaviors.

The field of evolutionary psychology explores the idea that certain behaviors have been selected for during the course of evolution.

Genetic discrimination in health insurance in US

Main article: Genetic discrimination

In the United States, the Genetic Information Nondiscrimination Act, which was signed into law by President George W. Bush on May 21, 2008, prohibits discrimination in employment and health insurance based on genetic information.

How to Predict Genetic Predisposition

There are several approaches commonly used in the field of genetics to predict a genetic predisposition toward a disease.

• Genome-Wide Association Studies (GWAS): studies that identify genetic variants linked to diseases by analyzing genomes across populations. This approach looks for single nucleotide polymorphisms (SNPs) associated with a specific disease or trait.
• Polygenic Risk Scores (PRS): approach that combines the influence of multiple genetic variants and provides a measurable score for an individual's likelihood of developing certain conditions. Research around this approach is focused on predicting heart disease, cancer, and psychiatric disorders.
• Machine learning algorithms: the use of algorithms that integrate genetic data that have improved prediction accuracy for certain conditions, including diabetes and some cancers.
• Nomogram models: technique that combines genetic markers and clinical indicators to produce personalized risk assessments.

Genetic predisposition at the molecular level

As individuals, one’s genetic makeup or genotype, which is passed down from their parents, defines how they look and what genetic conditions they could have inherited, or be at risk for. These traits are exclusive, and therefore one's susceptibility to specific diseases is unique as well. The inheritance of specific genes reflect phenotypes based on one allele that comes from the mother and one from the father of each gene .

Phenotypes that display genetic conditions are often caused by random mutations within the DNA sequence that makes up a gene. Somatic mutations are mutations that occur within the DNA of a non-reproductive cell post-conception, and therefore cannot be inherited, nor will they contribute to one’s genetic predisposition to disease. However, germline mutations occur within the DNA of reproductive cells and can be inherited by offspring, thereby influencing the individual's susceptibility to the specific genetic issue . Upon diagnosing individuals of particular conditions via genetic testing, their genetic predisposition can be measured with pedigree trees. These trees trace inheritance patterns throughout a family to see if the mutation of interest can also be found in other blood-related individuals.

Genetic disease inheritance patterns

Genetic diseases can be autosomal recessive, autosomal dominant, X chromosome-linked recessive, X chromosome-linked dominant or Y chromosome-linked. They will be inherited differently based on their composition. Autosomal inheritance patterns will affect specific autosomes, non-sex chromosomes, depending on the genetic disease. Autosomal recessive diseases occur only when both inherited alleles have the mutation, while autosomal dominant diseases will be demonstrated in individuals with only one mutant version of the allele. Therefore besides solely inheritance, the type of disease that is being considered plays a large role in how susceptible one is. Genetic disease predisposition can also be impacted by one’s gender, as sex chromosomes define inheritance of X-linked and Y-linked alleles. Males are far more likely to inherit X-linked recessive diseases, because they only have one copy of the X chromosome, while females have two and therefore need both to be mutated for this phenotype to be demonstrated. X-linked dominant diseases are equally shown in both males and females, while Y-linked diseases will only be demonstrated in males, as females do not have a Y chromosome .

See also

• Human nature
• Nature versus nurture
• Behavioral genetics
• Predispositioning Theory
• Psychiatric genetics
• Gene-environment correlation
• Eugenics
• Eggshell skull
• MODY
• Allergy
• Oncogene
• Quantitative trait locus
• Genetic privacy

References

1. ^ The results of this survey are discussed here (January 20, 1998).
2. ^ A summary of U.S.A. executive orders and proposed legislation is compiled by the National Center for Genome Resources.
3. ^ The Intentional Stance (MIT Press; Reprint edition 1989) (ISBN 0-262-54053-3)

External links

• Genetic discrimination fact sheet from the National Human Genome Research Institute.