Mrs. Stewart Biology Pedigree Charts

Objectives Can create a pedigree using family history information Can analyze a pedigree for genotypes Can predict inheritance for a genetic trait/disorder

What is a pedigree? Pedigrees are a “family tree” that is used to show the inheritance of genetic traits/disorders

Pedigree Charts Why do we use them? Then what information do we use to determine inheritance of traits? Record ancestry and/or trace the geneology of a trait through the family lines Genetic Testing Medical History Historical Data Family Records

Symbols

Pedigree Charts - Symbols

Pedigree Chart - Symbols

Symbols Check: Is person I-2 male or female? How are II-1 and II-3 related? List two people who are a couple. Who is the grandmother of person III-1?

Create a pedigree Using the family history below, create a pedigree: Anne and Max are brother and sister. Anne is 35 and Max is 33. Their parents are Kate and Joe. Anne is married to Curtis, and they have 3 kids: Devon (f), Ken (m) and Kimberly (f). Max is married to Natalie and they have 2 kids: Ryan (m) and Donna (f). Max, Curtis and Donna all have cystic fibrosis.

Pedigree Check

How do we read a Pedigree? Which family members are Albino? How is albinism inherited? Bill Sam Dominant or recessive? Autosomal or sex-linked?

Pedigrees

What are Inheritance Patterns? Inheritance Pattern: The transmission of genetically encoded traits/conditions/diseases to offspring In other words: How the gene is transmitted/passed on.

What are the different ways a genetic condition can be inherited?

Autosomal Recessive Skips generations Affects males/females equally Pedigree may show carriers

Autosomal Dominant There will not be carriers – those with the gene will be “affected” Will probably not skip generations Will affect males/females equally

Sex-Linked Recessive More males affected than females Skips generations

Example: Hemophilia in the royal family

How is Hemophilia inherited? Sex-Linked Recessive Disorder

Example: Hemophilia in the royal family What are some clues that you can see in this pedigree that could tell you this is a sex-linked disorder?

Pedigrees Albinism Polydactyly

Pedigree Chart

What is the inheritance pattern for this disorder?

Autosomal Recessive How do we know? “affected” skips generations carriers

Pedigree Practice: How is the trait inherited? What is the genotype of person II-3? Should persons II-1 and II-2 get checked to see if they are carriers? Autosomal Recessive Carrier - heterozygous Yes

Pedigree Practice: How is the trait inherited? What is the genotype of person II-3? Are there carriers for this trait? Autosomal Dominant Homozygous recessive No

Assignment: Complete pedigree worksheet packet