Example of Trait = Albinism Pedigree Charts Show relationships within a family In genetics: Used to show how an inherited trait is passed through a family Example of Trait = Albinism

Symbols Circle = female Square = male Normal or without trait = unshaded Trait = shaded

Symbols If an individual has one recessive allele for a trait, the person is a carrier. This is shown with a half-shaded square or circle.

Symbols Married couple or couple producing offspring = horizontal line connecting midpoint of circle and square

Symbols One offspring Multiple Offspring How do you differentiate between a brother and sister and a husband and wife on a pedigree? Multiple Offspring

Generations Each generation is (often) labeled with a Roman numeral. Oldest generation at top of pedigree Current generation at bottom

Generations Individuals in each generation may be numbered or named. 1 2 1 2 3 4 5 6 1 2 3 4 5 Individuals in each generation may be numbered or named. Siblings are placed in birth order from left to right.

Analysis How many offspring were produced by generation 1? Number of boys? Girls? How many of generation II were married with children? Deaths are shown with a slash. 1 2 1 2 3 4 5 6 1 2 3 4 5

Traits Autosomal recessive traits Autosomal dominant traits Sex-linked traits Autosomal- all other chromosomes Sex-linked- X or Y chromosome

Autosomal Recessive Appears only in individuals who receive TWO copies of the affected allele (one from each parent) Male and females (roughly) equally affected Does not appear in every generation

Autosomal Recessive

Analysis of a Recessive Trait How many individuals on this pedigree have the trait? How many are carriers?

Sickle Cell Anemia

Sickle Cell Anemia Red blood cell disorder Changes shape of blood cell Not flexible and can stick to vessel walls Causes blockage that slows or stops the flow of blood Oxygen cannot reach nearby tissues

Autosomal Dominant An alteration in ONE copy of the affected gene (allele) is enough to lead to disease Male and females (roughly) equally affected Does not skip a generation

Autosomal Dominant

Dominant or Recessive Trait?

Dominant or Recessive Trait?

Sex-linked traits If a gene is found on the X chromosome Males exhibit more often than females Females: XX (would need to inherit from the mother AND father) Males: XY (only need to inherit from the mother) Example: red-green colorblindness

Disorders Autosomal recessive cystic fibrosis Albinism Beta- thalassaemia Sickle cell Autosomal dominant Dwarfism Huntingtons Marfan syndrome Neurofibromitosis Tuberous Schlerosis Sex linked Hemophilia Duchennes muscular dystrophy Beckers muscular dystrophy Red-green colorblindness