lecture 8 - non-mendelial inheritance and multifactorial genetics Flashcards
(22 cards)
What are non-Mendelian inheritance patterns?
Inheritance patterns that do not conform to Mendelian genetics, indicating other factors at play beyond single-gene effects.
These patterns include codominance, incomplete dominance, multiple alleles, and polygenic traits.
What is codominance?
A situation where both alleles are expressed equally in the heterozygote phenotype, with neither allele masked.
Both traits appear distinctly in the phenotype.
What is incomplete dominance?
A type of inheritance where the offspring exhibits a phenotype that is intermediate between the phenotypes of both parents.
The traits do not blend but rather create a new phenotype.
What are multiple alleles?
Genes that have more than two alleles, such as the ABO blood type system in humans.
Different combinations of alleles lead to different blood types: A, B, AB, and O.
What are polygenic characteristics?
Traits controlled by multiple genes, each of which may have two or more alleles.
Traits like height and skin color are influenced by several genes.
What is polygenic inheritance?
Inheritance where multiple genes contribute to a single trait, leading to a range of phenotypes.
Adult height is an example of polygenic inheritance.
What is the normal distribution in polygenic inheritance?
A pattern where traits like height show a continuous distribution due to the additive effects of multiple genes.
This results in a bell curve when plotted.
What are multifactorial diseases?
Diseases that arise from the interplay of genetic and environmental factors, such as diabetes, cancer, and cardiovascular diseases.
Mental and neurodegenerative diseases also fall into this category.
How do genetics and environment interact in disease development?
Genetic predisposition combined with environmental triggers contributes to disease outcomes.
Example: FH gene mutation and dietary cholesterol.
What is the significance of the 1-antitrypsin mutation?
It increases sensitivity to environmental factors like smoking or dust, leading to diseases such as COPD or pulmonary emphysema.
Smoking is noted as a major risk factor.
What is the role of acetaldehyde dehydrogenase in alcoholism risk?
Deficiency leads to increased acetaldehyde levels, causing unpleasant symptoms after alcohol consumption.
This aversive reaction can deter alcohol use.
What is precision therapy?
Tailored medical treatments based on genetic information to optimize patient care.
It considers individual genetic responses to treatments.
What methods demonstrate genetic susceptibility?
Family and twin studies, heritability assessments, and polymorphism association studies.
These methods help identify genetic influences on traits and diseases.
What is heritability?
A mathematical estimate of the genetic vs. environmental contributions to a trait.
It is assumed that families or twins share similar environments.
What are single-nucleotide polymorphisms (SNPs)?
Common genetic variations that can occur in coding and non-coding regions of genes.
They are used in association studies to identify genetic risk factors.
What is the purpose of genome-wide association studies (GWAS)?
To identify genetic variants linked to diseases by comparing SNP frequencies in affected vs. unaffected individuals.
GWAS helps remove bias from candidate gene studies.
What does the term ‘concordance’ refer to in twin studies?
The degree to which both twins share a trait, indicating genetic influence.
Higher concordance in monozygotic (MZ) twins suggests a stronger genetic component.
What is the significance of familial clustering?
It involves observing affected individuals within families to determine genetic disease prevalence and risk.
This can help in understanding the inheritance patterns of diseases.
What are the limitations of association studies?
Candidate gene bias, low probability of selected candidates being associated, and the need for large, diverse samples.
Association does not imply causation.
What is coronary artery disease (CAD)?
A progressive condition characterized by atherosclerosis that narrows arteries, reducing blood flow to the heart.
CAD is influenced by both genetic and environmental factors.
What is the role of GWAS in identifying genetic variants?
It involves sample collection, genotyping, data analysis, and variant identification to link genetic variants to diseases.
This process helps in understanding complex genetic conditions.
What are the key take-away messages regarding genetic and environmental factors?
Diseases arise from both genetic and environmental factors, and investigations should include family studies and GWAS.
GWAS generates extensive data but association does not equate to causation.
