Analyzing family relationships for genetic clues

  • Published on
    17-Jan-2018

  • View
    217

  • Download
    0

Embed Size (px)

DESCRIPTION

Pedigree diagram A pedigree is a diagram of the individuals and their relationships in a family group. People are represented by symbols. Lines show the connections between people. Purpose: To determine the mode inheritance of a genetic disease. To estimate the risk of passing on a genetic disease.

Transcript

Analyzing family relationships for genetic clues
Pedigrees Analyzing family relationships for genetic clues Pedigree diagram A pedigree is a diagram of the individuals andtheir relationships in a family group. People are represented by symbols. Lines show the connections between people. Purpose: To determine the mode inheritance of a geneticdisease. To estimate the risk of passing on a genetic disease. Symbols Males are square. Females are round.
Affected individuals aredark. Normal or unknown arewhite. Horizontal lines arematings.Parents Vertical lines arebetween generations Who is who? The oldest generation is at the top of the diagram.
Newest generation is atthe bottom. Generations are countedfrom the oldest generationusing Roman numerals. Count top to bottom Individuals can benumbered. Left to right Three Types of Inheritance
Each type has a distinctivepattern Autosomal Dominant Autosomal Recessive Sex-Linked Recessive Autosomal Dominant Present in each generation. No skipping.
Males and Femalesare equally likely tobe affected. Each affected personhas an affectedparent. Unaffected personhas unaffectedoffspring.WHY? Autosomal Recessive Must be homozygous to be expressed.
If child is rr, thenthe parents must be_____. Recessive can skipgenerations. Sex-Linked Recessive Recessive may skip generations.
Males have one X, andmales are more likely tobe affected. Never passes fromfather to son. An affected male getshis X from his mom, II-2. What is her genotype? X Xc or Xc Xc Test the pedigree for a pattern
Mark the genotypes. Try the three patterns. What pattern is possible? Usethese letters for Sex Linked only. XA = normalXa = the trait (a genetic disease or abnormality)Y = Y chromosome (males only) Autosomal DominantAutosomal RecessiveSex-Linked Recessive Autosomal Dominant Autosomal Recessive Sex-Linked Recessive
What is the pattern? Mark the genotypes. Try the three patterns. What patterns are possible? Usethese letters for Sex Linked only. XA = normalXa = the trait (a genetic disease or abnormality)Y = Y chromosome (males only) Autosomal DominantAutosomal RecessiveSex-Linked Recessive Autosomal Dominant Autosomal Recessive Sex-Linked Recessive
What is the pattern? Mark the genotypes. Try the three patterns. What pattern is possible? Usethese letters for Sex Linked only. XA = normalXa = the trait (a genetic disease or abnormality)Y = Y chromosome (males only) Autosomal DominantAutosomal RecessiveSex-Linked Recessive Create a Pedigree Put the male parent to the left of the female. (I generation) Draw a horizontal line between parents. Draw a line down from the parents to a horizontal lineconnecting a group of brothers and sisters. (II generation) Siblings are entered with the oldest to the left and youngestis to the right. Draw a line across between a sibling and their spouse.Drawdown from this line to their children (grandchildren of Igeneration).(IIIgeneration) Darken all individuals who are affected. Mark carriers with a half dark/half light symbol. Check your understanding
What can you conclude about the parents of a personthat has a dominant characteristic? (Check the correctanswer below.) --If a person has a dominant trait, the parents will nothave the trait. --If a person has a dominant trait, the parents mighthave the trait or they might not have it. --If a person has a dominant trait, at least one of theparents will have the trait. --If a person has a dominant trait, both of the parentswill have the trait. Test an Autosomal Dominant
Can two individuals that have anautosomal dominant trait haveunaffected children? (Check the correctanswer below.) --If two individuals have a dominanttrait, none of their offspring will havethe trait. --If two individuals have a dominanttrait, their offspring might or might nothave the trait. --If two individuals have a dominanttrait, their offspring will have the trait. Mark the Genotype What is the pattern? Label the generations. Number the people.
Mark the genotypes. Dominant/Recessive? Autosomal/Sex-linked? What is the pattern?___________________ Dominant or Recessive? Autosomal or Sex-linked?
What is the pattern? _______________ Trace the lines between IV-4 to the oldest personwith the trait. Dominant or Recessive? Autosomal or Sex-linked?
What is the pattern? _______________ Label genotypes.Start with the affectedindividuals. Dominant or Recessive? Autosomal or Sex-linked?
What is the pattern? _______________ Which person is the best clue? __________ Resources McClean, Phillip, 2000, Mendelian Genetics, NorthDakota State University,mendel/mendel9.htm Tissot, Robert, 2014, Human Genetics, University ofIllinois Chicago,tml#Sample

Recommended

View more >