Inheritance of Traits: Pedigrees

Pedigree definition Pedigree: a family history that shows how a trait is inherited over several generations Pedigrees are usually used when parents want to know if they are carriers of a particular disorder Carriers are heterozygous for a disorder and don’t show symptoms, BUT have the allele to pass on to their offspring

Making a Pedigree Filled in symbols indicate individual is affected with a disorder Female Male Married Couple Siblings

Example of a Pedigree Do any disorders run in this family?? Grandparents Grandparents Parents Aunts, Uncles Aunts, Uncles Brother You Do any disorders run in this family??

Interpreting a Pedigree What can you tell from a pedigree? Whether a family has an autosomal or sex-linked disease or disorder Autosomal disorder: appears in both sexes equally Sex-linked disorder: allele is located only on the X or Y chromosome. Most sex-linked genes are on the X chromosome and are recessive So who would have an X-linked disorder more often, boys or girls? Whether a disorder is dominant or recessive

Is this disorder 1) autosomal or sex linked, 2) dominant or recessive? Grandparents Grandparents Parents Aunts, Uncles Aunts, Uncles Sex Linked! (in this case allele is recessive and located on the X chromosome) Brother You

Is this disorder 1) autosomal or sex linked, 2) dominant or recessive? Grandparents Grandparents Parents Aunts, Uncles Aunts, Uncles Autosomal dominant! Brother You

Is this disorder 1) autosomal or sex linked, 2) dominant or recessive? Grandparents Grandparents Parents Aunts, Uncles Aunts, Uncles Autosomal recessive! Brother You