Ultimately, the goal of genetics is the analysis of the genotype of organisms. But the genotype can be identified – and therefore studied – only through its phenotypic effect. This means that two genotypes are recognised as different from each other because the phenotypes of their carriers are different. A problem can be seen with this approach as the actual variation between organisms is usually quantitative, not qualitative. Many different genotypes may have the same average phenotype. At the same time, because of environmental variation, two individuals of the same genotype may not have the same phenotype. This lack of a one-to-one correspondence between genotype and phenotype obscures underlying Mendelian genetics. I am going to explore the use of various statistical techniques for studying quantitative traits with application to behavioural traits. I am also going to examine whether there are behavioural traits with sufficiently high heritabilities to give hope for gene searches and I am going to discuss the difficulties that confront molecular geneticists regarding psychiatric genetics.
Inhaltsverzeichnis (Table of Contents)
- Quantitative Genetics and Complex Trait Analysis in Humans
- The Genetic Basis of Complex Diseases
- The Concept of the Statistical Distribution
- Correlation between Two Variables
- The Difference between Quantitative and Mendelian Traits
- The Phenotypic Distribution of a Trait
- Heritability
- Methods for Establishing the Heritability of a Trait
- The Difficulty of Separating Environmental from Genetic Similarities in Humans
- Familiality vs. Heritability in Human Behavioural Traits
Zielsetzung und Themenschwerpunkte (Objectives and Key Themes)
This text aims to explore the application of quantitative genetics to the study of complex traits in humans, particularly focusing on the genetic basis of complex diseases. It seeks to understand how quantitative genetic methods can be used to unravel the interplay between genetics and environment in shaping human traits.
- Quantitative genetics and its application to complex human traits
- The nature vs. nurture debate in relation to complex traits
- The challenges of studying genetic influences on human behaviour
- Methods for determining heritability of traits
- Distinguishing between familiality and heritability
Zusammenfassung der Kapitel (Chapter Summaries)
- Quantitative Genetics and Complex Trait Analysis in Humans: Introduces the concept of quantitative genetics and its importance in understanding complex traits. It highlights the difficulty in separating genetic and environmental influences, particularly in human studies.
- The Genetic Basis of Complex Diseases: Discusses the role of genetics in complex diseases and the challenges of identifying specific genes involved. It explores the use of statistical techniques for studying quantitative traits.
- The Concept of the Statistical Distribution: Explains the basic statistical concepts necessary for understanding quantitative traits, including frequency distributions, mean, variance, and standard deviation.
- Correlation between Two Variables: Introduces the concept of correlation and its significance in studying the relationship between variables. It discusses how correlation can be used to understand the influence of environment on heritable characters.
- The Difference between Quantitative and Mendelian Traits: Explores the distinction between quantitative and Mendelian traits, emphasizing the role of multiple genes and environmental factors in shaping quantitative traits.
- The Phenotypic Distribution of a Trait: Discusses the impact of both genetic and environmental factors on the phenotypic distribution of a trait. It introduces the concept of the norm of reaction.
- Heritability: Explains the concept of heritability and how it differs from familiality. It emphasizes the importance of separating shared genetic and environmental influences when studying heritable traits.
- Methods for Establishing the Heritability of a Trait: Describes two main methods for determining heritability, including phenotypic similarity between relatives and marker gene segregation.
- The Difficulty of Separating Environmental from Genetic Similarities in Humans: Examines the challenges of separating environmental and genetic influences in human populations due to shared family environments.
- Familiality vs. Heritability in Human Behavioural Traits: Discusses the distinction between familiality and heritability in human behavioural traits, highlighting the importance of adoption studies in disentangling these factors.
Schlüsselwörter (Keywords)
Key concepts explored in this text include quantitative genetics, complex traits, heritability, familiality, environmental influences, genetic influences, statistical distribution, correlation, phenotypic variation, and adoption studies. These terms form the foundation for understanding the genetic basis of complex traits in humans and the challenges of disentangling nature and nurture.
- Quote paper
- BA (Oxon), Dip Psych (Open) Christine Langhoff (Author), 2002, Quantitative genetics and complex trait analysis in humans; the genetic basis of complex diseases, Munich, GRIN Verlag, https://www.grin.com/document/14019
