Lesson 14: Heritability learn about the methods for studying traits to determine if genes influence them; specifically learn about how to analyze data from twin studies; and understand the genes that influence alcoholism specifically and addiction generally.

Genes controlling drug use?!?!? Activity 1 Separated at birth, the JIMS. What did you think about that?

How would you study the role of genes? How would you determine if a trait was inherited? Activity 2 1. Does the trait run in families? 2. Do individuals with genetic identity share the trait more than those without? 3. With non-humans: Selective Breeding

Question: Members of a local “Alcoholics Anonymous” meeting got to talking about their parents. They couldn’t help but notice that a very large number of them had an alcoholic parent. In what way is this inadequate evidence that alcohol addiction is genetically controlled?

How to map families: Displaying Phenotypes Pedigree Analysis: shaded = ? displays trait (may or may not be genetic)

What do you think could be the Mendalian genotypes? Dominant vs. Recessive Can this work? aa A_ aa A_ aa A_ aa A_ aa A_

Displaying Phenotypes-try this one Hatched symbol – intermediate phenotype (incomplete dominanace) Aa What is wrong with this pedigree? What do we need to change to make this work? ??

A REAL pedigree: what do you think is the inheritance pattern? aa ?? aa twins Aa Autosomal dominant

A REAL pedigree: what do you think the inheritance pattern is? ??

If we call the gene for the trait on the previous pedigree “A”, what is the red circled woman’s genotype ? 1.Affected 2.Unaffected 3.AA 4.Aa 5.aa 6.Insufficient information

Could this trait (filled in symbol is a heroin addict) be controlled entirely by genes? 1.Sure 2.No way – addiction is not genetic 3.No way – phenotypes are not consistent with expectations 4.Not enough information

How alike are twins? Activity 3 RelationshipParent – child Sibling (non twin) Fraternal twins Identical twins Genetic similarity 50% 25% 99.99%

What do twins look like in pedigrees?

What is the difference between concordant and discordant in twins? Are fraternal twins more likely to be concordant or discordant for a trait? What about identical twins? Does it matter if they are raised apart or together?  If high concordance among identical twins, raised apart, trait can be said to be VERY influenced by GENETICS

How do these studies tell us about genetic influence of alcoholism? Activity Likelihood of becoming an alcoholic IT concordanceFT concordance 76% 61% 36% 25%

A trait that is, at least partially, genetic will show which of these relationships? 1.Higher concordance values for males than females 2.Higher concordance values for identical twins than fraternal twins 3.Higher concordance values for twins reared together than twins reared apart 4.Higher concordance values for mother-son than father-daughter

Can one have an addictive personality? Activity6 Discuss with your table group: cite evidence from the following presentations: Bar Flies: alcoholism in fruit flies Alcoholism genes How do genes impact addiction Other factors So, is there an alcoholic gene?

Genes that encode response proteins: Activity 4 What type of genes should we consider when talking about drugs? Genes that encode receptors (for drugs or NT) Genes that encode enzymes (for drugs or NT) Genes that encode recycling transponders (for NT)

How does genetics relate to alcoholism? D2DR ALDH GABA receptors  Started with SNP analysis Serotonin transporters Poor dopamine binding – crave more opportunities for dopamine release Good aldehyde metabolism, fewer side effects, happy to continue to drink Less GABA binding – less you notice alcohol’s effects Great serotonin recycling, more you turn to alcohol to self-medicate poor mood

Even with all this genetic info, does this mean one WILL be an alcoholic?

From this pedigree for the trait (abuse of heroin), we can conclude that: 1.Heroin abuse is common 2.Heroin abuse is dominant 3.Heroin abuse is recessive 4.Heroin abuse is genetically controlled 5.We can’t conclude that genes totally control heroin abuse at all

Candidate Gene Approach: How can genes affect behavior? Activity 7 How do your genetics affect your response to nicotine?

Which of the following best describes reward deficiency syndrome? Activity 8 READ NOW 1.There is too little dopamine produced by the brain 2.The dopamine is recycled too fast to give pleasure 3.There are less than normal numbers of the D2DR receptors 4.Glutamate is released instead of dopamine 5.GABA inactivates the dopamine

What are pharmacogenetics? Discuss your findings from Activity 9 Why might it be beneficial – how will it change medicine?

Aside from genes, discuss some of the risk and protective factors that can influence addiction: Activity 10 What were your findings from the Healthy Youth Survey results?