Multifactorial/Common Complex Disorders Flashcards
What are the causes of common complex conditions
Multifactorial inheritance
Mendelian inheritance
What are the causes of multifactorial inheritance
Environment
Inherited predisposition due to multiple genetic factors
How do we identify genetic and env. influences
Observational studies of incidence of disease in different groups
Eg. twin studies, adoption studies
What is the heritability of condition
Proportion of aetiology ascribed to genetic factors
What does polygenic inheritance mean
Each gene makes small additive effect to final phenotype
Basis for continuous traits following normal distribution
What is the threshold libability
Above this liability, people will develop multifactorial disease
What are the factors that increase probability of recurrence
High heritability
Person with condition of more rarely affected sex
Severe/early onset
Multiple family members affected
How do we identify genetic factors involved in condition
Identify pedigree pattern
Diagnose disorder
Identify genes using linkage or gene tracking
Do genes in the location affected have functions suggesting cause of disease
Genes in location then sequenced for pathogenic mutation
What is association
Occurence together in population more often than can be readily explained by chance of >2 traits
What are the questions to ask once area of chromosome is identified
Is it protein coding region
Are there controlling elements in area
Any variants
Why is genomics important in clinical practice
Targeted treatment
Genetics can alter drug response
Can change environment for genetically susceptible individuals
What does mutation in SNP suggest according to GWAS
May not be direct cause of disease but serves as marker of other genetic factors in chromosomal region
