Biological explanations

• What percentage of genes do fraternal twins share?

  50%
• How do adoption studies differentiate between genetic and environmental influences?

  By comparing adopted individuals with biological and adoptive parents
• How does the case of fraternal twins Sara and Lisa contribute to understanding schizophrenia?

  It shows variability in genetic risk
• What is the purpose of adoption studies in schizophrenia research?

  To separate genetic and environmental influences
• What do adopted individuals share with their adoptive parents?

  Shared household environment
• What is the role of candidate genes in schizophrenia?

  • Contribute to the genetic risk of schizophrenia
• What is the genetic source of schizophrenia risk?

  Genes passed from parents
• What is the chromosome number with the highest log(p) value?

  22
• What are the two main factors influencing schizophrenia?

  • Genetic factors
  • Environmental factors
• What is the function of the DRD2 gene?

  It controls dopamine receptors
• What do adopted individuals share with their biological parents?

  50% of their genes
• What are candidate genes?

  Genes believed to play a role based on function
• What does the comparison between an adopted individual and their biological parent indicate?

  It indicates the role of genetic factors
• What can you infer about the genetic architecture of the trait or disease based on the distribution of points across the chromosomes?

  • The trait or disease is likely influenced by multiple genetic variants across the genome
  • Some chromosomes show stronger associations than others, suggesting certain regions may harbor variants with larger effects
  • The distribution of points suggests a polygenic architecture rather than a single major locus
• What is the relationship between genetic predispositions and environmental triggers in schizophrenia?

  Genetic predispositions can be triggered by environmental factors
• What is the specific gene mentioned as a candidate gene for schizophrenia?

  DRD2
• If an adopted person develops schizophrenia and their biological parent has the condition, what does this suggest?

  It suggests a genetic influence
• If an adopted person develops schizophrenia and their adoptive parents have it, what does this indicate?

  It indicates an environmental factor
• What does the comparison between an adopted individual and their adoptive parent show?

  It shows the influence of the environment
• What is the y-axis of the graph showing?

  The log(p) value
• What do molecular genetic studies help identify in relation to schizophrenia?

  Specific genes linked to schizophrenia
• What is the x-axis of the graph showing?

  The chromosome number
• What are the key comparisons made in adoption studies for schizophrenia?

  • Adopted individual vs Biological parent:
  • Genes Shared: 50%
  • Environment Shared: None
  • Relevance: Indicates genetic factors
  • Adopted individual vs Adoptive parent:
  • Genes Shared: 0%
  • Environment Shared: Shared household
  • Relevance: Indicates environmental factors
• What does the log(p) value represent in this graph?

  The statistical significance of the association between genetic variants and a trait or disease
• If an individual has Genotype 1, how might their Phenotype differ from someone with Genotype 2 in the same Environment?

  Their observable characteristics would be different
• If identical twins both develop schizophrenia, what does this imply?

  There is likely a genetic influence
• How do the three elements in the image interact?

  • Genotype 1 and Genotype 2 interact with the Environment to produce the Phenotype
  • The Phenotype is the observable characteristics that result from the interaction between the Genotypes and the Environment
• What does a higher concordance rate in identical twins suggest about schizophrenia?

  It indicates a strong genetic component
• What is the inheritance level of genetic factors in schizophrenia?

  High
• What are the implications of the relationship between Genotype and Environment in determining Phenotype?

  • Genotype alone does not determine Phenotype, the Environment also plays a key role
  • Changes in the Environment can lead to different Phenotypes, even with the same Genotype
  • Understanding the Genotype-Environment interaction is important for predicting and understanding Phenotypic variation
• What limitation do family studies have compared to twin studies?

  They don't control for shared environments as well
• If Sarah inherits genes that increase her risk for schizophrenia, what might trigger the illness later in life?

  Significant stress
• What is the inheritance level of environmental factors in schizophrenia?

  Low
• How does dysregulation of the DRD2 gene affect schizophrenia symptoms?

  It affects dopamine signaling, causing positive symptoms
• Does inheriting genes for schizophrenia guarantee the condition will develop?

  No, it increases risk but is not certain
• Why is understanding the genetic basis of schizophrenia important?

  It helps identify genetic predispositions and vulnerabilities
• How do twin studies assess the heritability of schizophrenia?

  By comparing concordance rates of twins
• What are the differences between GWAS and candidate gene studies?

  • GWAS:
  • Entire genome
  • Identifies novel risk genes
  • High throughput
  • Candidate gene studies:
  • Specific genes
  • Targeted and hypothesis-driven
• What are genome-wide association studies (GWAS)?

  Tools for identifying genetic risk factors
• What does the overall distribution of points across the chromosomes suggest about the genetic architecture of the trait or disease?

  It suggests a polygenic architecture with multiple genetic variants contributing