Genetic Pedigree workshop

Question 1

What is meant by a genetic pedigree?

Answer 1

A visual representation of several generations of a family, showing patterns of inheritance.
Uses standardises symbols and lines to represent the relationship between different family members

Question 2

How are different genders represented on a genetic pedigree?

Answer 2

Male = square
Females = circle
Sex unknown + diamond

Question 3

How is an affected v non-affected individual respresented on a genetic pedigree?

Answer 3

Affected are coloured in black, non- affected are left white.

Question 4

How are deceased indivduals represented on a gentic pedigree?

Answer 4

Crosses through their shape with a diagonal line

Question 5

How are pregnant indivduals represented on a genetic pedigree?

Answer 5

Letter P within the child shape
Child line as a diamond still shown

Question 6

How is a miscarriage represented on a genetic pedigree?

Answer 6

A white triangle is drawn in the line of descent, gender is written below the triangle, if the gender is not known then it is not written.

Question 7

How is the person providing the information for the genetic pedigree indicated on the genetic pedigree?

Answer 7

A 45 degree arrow is drawn pointing the the bottom left corner of the individuals shape.

Question 8

How is a divorce represented on a genetic pedigree?

Answer 8

Two diagonal (slant to the right) lines are drawn through the partnership line

Question 9

How is a relationship between to blood relatives shown (incest) in a genetic pedigree?

Answer 9

A double line is used as the relationship line

Question 10

How are identical twins identified compared to normal siblings on a genetic pedigree?

Answer 10

Do not have a separate individual line from the line of descent

Question 11

How are non-identical twins shown on a genetic pedigree?

Answer 11

Question 12

What are the more scientific terms for identical and non-identical twins?

Answer 12

Identical = monozygotic
Non-identical = dizygotic

Question 13

What additional information might be recorded under a persons shape on a genetic pedigree?

Answer 13

Name
Date of birth
Relevant symptoms, diagnoses and age at diagnoses
Cause of death and age at death
Pregancy and birth history
Occupational/environmental exposures
medications

Question 14

What is genetic relatedness?

Answer 14

The proportion of alleles that two indivudals share due to recent common ancestory.
This excludes alleles shared simply because they are the same species

Question 15

How is Mendels law of segregation used to calculate genetic relatedness?

Answer 15

Mendel believes that each parent passess half of their genetic material to their offspring.
Therefore, each downwards in geneteration x0.5
Hence parent and child - 50%
Grandparent and child - 25%

Question 16

How does Sewall Wrights Method allow for calculation of genetic relatedness?

Answer 16

Genetic Relatedness = 1/2 to the power of n + (repeat if second individual is linked by another path)
n = number of links between relatives in the path that includes the common ancestor

Question 17

When can Sewall Wrights Method to calculate genetic relatedness not be used?

Answer 17

When monozygotic twins are in the family tree, they share all their alleles hence their relatedness and their descendents can not be directly calculated in this way.

Question 18

What is a mendelian v non-mendelian condition?

Answer 18

A mendelian condition is goverend by the inheritance of a dominant or recessive single gene
A non-mendelian condition is not and often involves multiple genes.

Question 19

What are Mendels Laws?

Answer 19

Law of segreation: indivduals have two units of inheritance (two alleles per locus) but only one allele is transmitted to the offspring
Law of independent assortment: genes segregate independently. (liklihood of inherting A does not change the likelihood of inheriting B)

Question 20

Explain with p + q = 1, what does each letter respresent.

Answer 20

P chance of inheriting the dominant allele
q change of inheriting the recessive allele
Of the same gene in one individual

Question 21

What is the Hardy-Weinberg Equilibrium?

Answer 21

Used to calculate the proportion of certain genotypes in a population where the allele frequencies are known. Assumes the allel frequency in a population remains constant over multiple generation
p2 + 2pq + q2 = 1
p2 = dominant homozygous
2pq = heterozygous
q2 = recessive homozygous

Question 22

What are the five assumptions of the hardy weinbergg equilibrium?

Answer 22

Large population
No mutation
No natural selection
No migration
Random mating

Question 23

What two different equation are used in the Hardy Weinberg Equilibrium?

Answer 23

Allele frequency - p+q = 1
Genotype frequency = p2 + 2pq + q2 = 1

Question 24

How should people in a relationship be organised on a genetic pedigree?

Answer 24

Male to the left
Female to the right

Question 25

How should siblings be organised on a genetic pedigree?

Answer 25

In order of birth
Oldest on the left.

Question 26

How do you show that family history is not available in a genetic pedigree?

Answer 26

Line from above the persons shape ending in a question mark

Question 27

How do you indicate no children by choice or known reason?

Answer 27

Couple link be relationship line go down from middle and out as it to make a branch for children outward but no children
Can be from a single person, if reason known right underneat

Question 28

How do you indicae infertility in a genetic pedigree?

Answer 28

Couple branch together, down and out as if to have children, make outwards branch double lined, if reasons known state underneath.

Question 29

How is adoption indicated in a genetic pedigree?

Answer 29

Dashed line from adoptive parent stem, child shape surrounded by square brackets.
Whn adopted out the child is shown linked to biological parents with a full line but is surrounded by sqaure brackets.

Question 30

What is a penetrance?

Answer 30

The proportion of individuals with a certain allele or mutations that exhibt the phenotype associated with their genotype.