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BIOL332 > Pedigrees > Flashcards

Pedigrees Flashcards

1
Q

What is the value of a pedigree

A
  1. Social connection –> Shows connecteness
  2. Follow alleles through meiosis (Genetic pedigree)
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2
Q

How to label individuals in a pedigree

A

Row number – give each row (each generation) a Roman numeral

Individual Number – Give each indivual in the row a number (INCLUDE ALL INDIVUALS IN THE ROW NOT JUST CHILDREN)
- Cpount Left to right and assign each indiviual a number

Affected or not affected
Filled in = Affected
Not filled in = not affected

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3
Q

Labeling Individuals in pedigree example

A
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4
Q

Sex in a Pedigree

A

Square = Male

Circle = Female

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5
Q

Proband

A

The individual with an arrow pointing at them in the pedigree – this is the individual that you got the information from
- Person who initiates pedigree – gives information

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6
Q

Value of the proband

A

Because when making a pedigree = you are showing who you got the information from which is important because the infomration can get clouded as you move farther from the proband

***The information closer to the proband is more relaible

***Useful for clincials because it provides a condifence interval – individual is more liley to be accurate with immediate family
- if damily member is more distant you might be less confident in health information

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7
Q

What does // indicate in a pedigree?

A

Severed relationship

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8
Q

What does /\ indicated in a pedigree

A

Fraternal twins

Fraternal twins = siblings that were born at the same time

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9
Q

Practice – In the following pedigree assign the genotypes to everyone and indicate individuals that would be affected or carries

A

When filling this out:
1. Assume that anyone coming in as a spouse does not have the rare allele (is homozygous for the non-rare allele)
- Assume that spouses are all aa because it is a rtare allele = peope coming in are not carriers and do not have the trait

  1. When you have different pheontypes from teh cross = assume that they are evenly distributed between boys and grils
    Example – if have Aa and aa in the offpring – assume we have 4 kids (2 boys and 2 girls) – assume one boy and one girl is Aa and one boy and one girl is aa
    - need to be one boy and one girl (even between both boys and grils)
  2. Since this is a dominent trait and only need one allle – assume that the affected are heeterozygous (unless need to be homozygous from punnet square) – assume that they are heterozygous because rare allele
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10
Q

Safe assumtions in pedigree

A
  1. Assume that people entering are not carries (assume that non-blood relatives are not carriers)
    • IF you know the mode of inheritance and you know that in order for the pedigree to work then they MUST be a carrier then you can assume that they are a carroer
  2. Assume that is dominent trait and don’t know if the person is homozygous or heterozygous then they are heterozygous
    • For dominent traits – the first person in teh pedigree to show the trait is most likley heterozygous
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11
Q

What does this symbol mean (what does it mean if something is partially filled in)

A

Means that the individual is a carreier

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12
Q

Practice – In the following pedigree assign the genotypes to everyone and indicate individuals that would be affected or carries

A

We can assume that the spouses coming in are AA because a is rare

Remeber – that when have two genotypes – there needs to be an equala mount of boys and girls with that genotype
- If two genotypes –> have 4 kids (2 boys and 2 girls) and 1 boy and one girl is one genotype and one boy and one girl is the other genotype

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13
Q

Practice – In the following pedigree assign the genotypes to everyone and indicate individuals that would be affected or carries

A
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14
Q

Trends of passing X chromsome (general)

A

Males pass the X to all daughters and NO sons

Females = pass X to both daughters and sones (if have two diferent alleles on their X chromsomes thebn 1/2 the kids will get one of the tyoes of X and half the kids get the other type of X)
- AND – the passing of one type of X (half of them are boys and half are girls) AND the otehr half of kids that get the other X (Half of them are boys and half are girls)

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14
Q

Trends of passing X chromsome (general)

A

Males pass the X to all daughters and NO sons

Females = pass X to both daughters and sones (if have two diferent alleles on their X chromsomes thebn 1/2 the kids will get one of the tyoes of X and half the kids get the other type of X)
- AND – the passing of one type of X (half of them are boys and half are girls) AND the otehr half of kids that get the other X (Half of them are boys and half are girls)

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15
Q

Practice – In the following pedigree assign the genotypes to everyone and indicate individuals that would be affected or carries

A
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16
Q

Practice – In the following pedigree assign the genotypes to everyone and indicate individuals that would be affected or carries
***NOTE – the affected should be the male in the first generation

A
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17
Q

Practice – In the following pedigree assign the genotypes to everyone and indicate individuals that would be affected or carries

A

NOTES:
- Affected males don’t pass down the trait to kids
- Affected females pass down the trait to ALL kids

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18
Q

Where do you get mtDNA from?

A

Get ALL mtDNA from your mom

***ONLY the mom passes mtDNA to ALL kids

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19
Q

Weird think in mitocondrial pedigrees

A

HAS incomplete dominence
- Affected mom might have unefefcted kids and unaffecte dmom (that still has the mutation but doesn’t show the phenotype) might have affected kids

Can have an affected mother pas one the trait to one BUT NOT all of the kids (ALL of the kids get the mutated mtDNA but not all will show the phenotype)

Can have an unaffected mother (that has some mutated mtDNA) pass the mutation to kids and have affected offspring (She can have kids that show the phenotye BUT she does not show the phenotye BUT she must have a mutated allele because she has affected offspring)

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20
Q

Autosomal Dominent Trends

A
  1. Trait appears equally in males and females
  2. Trait doesn’t skip generations
  3. Affected children have an affected parent
  4. Unaffcted children do not transmitt the disease
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21
Q

Autosomal recessive traits Trends

A
  1. Trait appears equally in males and females
  2. Trait skips generations
  3. More appear among the progeny of related parents
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22
Q

What does ====== line in pedigree mean?

A

Means consigous relationship (Example – between first cousins)

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23
Q

X-Linked dominent Trait trends

A
  1. Trait does not skip generations
  2. Affected males pass the trait to all daughters and no sons
  3. Affected heterozygous females pass the trait to half of the sons and half of the daughters
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24
Q

X-linked Recessive Trait trends

A
  1. Affected males proudce carrier daughters
  2. No sons of affected males are affected
  3. Males are more likley to be affected than females
  4. Half of the sons of an unaffected carrier will be affected
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25
Q

Y-link Trait trends

A
  1. Traits ONLY appear in males
  2. All of the sons of affected males will be affected
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26
Q

mtDNA traits Trends

A
  1. Affected females pass the trait to ALL children
  2. Affected males never pass down the trait
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27
Q

Trend in mtDNA traits

A

Often show incomplete penetrance

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28
Q

Incomplete penetrance

A

When not every indivduals must be a particular genotype to show the expected phenotype
- Not everyone with teh allele shows the trait

Example – with mtDNA
- Can have an affected mother pas one the trait to one BUT NOT all of the kids (ALL of the kids get the mutated mtDNA but not all will show the phenotype)
- Can have an unaffected mother (that has some mutated mtDNA) pass the mutation to kids and have affected offspring (She can have kids that show the phenotye BUT she does not show the phenotye BUT she must have a mutated allele because she has affected offspring)

29
Q

Heteroplasmy

A

The Co-existance of multiple mtDNA variants in a single cell or among cells within an individual
- Different mtDNA can have different sequences

***mtDNA heteroplasmy = common in humans

30
Q

Amount of mtDNA in a cell

A

There are many copies of mtDNA in a cell – they don’t all need to be the same sequence
- You can have different type of mtDNA

31
Q

How is mtDNA inherited

A

NOT inheridted in mendialian ratios
- Since have random segaration AND you can have different sequances in mtDNA –> you can have some cell that get a lot of the mutated mtDNA and some that do not = thats the reason that a mom without the phenotype can have kids with mutant phenotype OR a mom that does have the phenotype can have kids without the phenotype

32
Q

Organelle Inheritance

A

DOES NOT follow mendialian ratios – have random segeragation of mtDNA during meiosis that leads to unequal inheriyance of mtDNA
- There is NO way to predict this – it is just where the mtDNA happens to be when segregating

**Image = shows that sometimes you coudl get more of teh blu mitocondria and sometime syou get more red during mitosis and meiosis – don’t know what varaiant of mtDNA will be in the highest concentration after cell division

33
Q

When does mitondrial disease arise

A

If the mtDNA varaint that contains a disease causing alelle reaches a certain tgreshold disease symtoms can arise
- If have a mom that has disease mtNDA they can
pass down enough copies for the child to have the disease through ranodm segration (because of random segregation the children can have more copies) OR through random segregation the child can have few copies
- It can increase when passed down to a point where the individuakl receives enough copies = starts to show the disease

34
Q

Carries of mtDNA diesease

A

A granddaught from a grandmother that has mutated mtDNA can have the diease even of her own mom does not have the diesease because her mom still has some copies of the mutant mtDNA but does not have enough for the threholf of disease

34
Q

Carries of mtDNA diesease

A

A granddaught from a grandmother that has mutated mtDNA can have the diease even of her own mom does not have the diesease because her mom still has some copies of the mutant mtDNA but does not have enough for the threholf of disease

35
Q

Pedigree

A

Genetic representation of a family tree

36
Q

Relationship line between spouse

A

Not genetically related but have a relationships

37
Q

Descent line (shows offspring)

A
38
Q

What does a slash through an individual mean in a pedigree

A

Dead

39
Q

Birth order in pedigree

A

The child all the way to the left is the 1st born – goes down from there (Be careful not to count spouses only look at siblings)

40
Q

Numbering people in pedigree

A

Each genertion = roman numberal

Each person in line is a number (left = 1) – includes everyone (Children and spouses)

41
Q

How do you indicate a severed relationship

A

Put dashes through the relationship line

42
Q

What do roman numeral indicate in pedigree

A

Indicate generation – everyone in that line is the same genertaion

Considered “generation line” – put everyone in the same generation in the same line

43
Q

Pedigrees are…

A

Social construction and genetic representation

44
Q

How do you show identical twins

A
45
Q

How do you show fratermal twins

A

Twins = born at the same time = lines going down start at the same point
- No line in the middle

46
Q

How do you show adopted kid

A

With a dotted line (rather than a solid decent line)
***Putting social context on pdeigree but indicates no genertic information was passed down

47
Q

Showing a father who was a sperm donor but has no relationship with daughter

A

Line goes to the mother but the duaghter only comes off of mother is not connected to the father

48
Q

What does a partially filled individual mean

A

The person is a carrier

49
Q

What does a diamond indicate

A

Individual does not fall neatly under male/female
- Could be trans or intersex or might not know gender yet

50
Q

Consigous relationship

A

Shown by double lines – is incest
- Might share the same mother

***Frowned upon in humans

51
Q

Pedigree (helpful reminders/symbols)

A
52
Q

Use of pedigrees

A

Can help genetocists understand how traits are inherited between genertions

53
Q

Example Sutosomad recessive disorders

A
  1. Sinckle cell – RBC diseae
  2. Cystic fibrcous – chloride chanel defect
  3. PKU – Phenylzalanine metabolism defect
  4. Tay Sachs – Lipid metabolism disorder

**Each are on a single gene – need 2 copies of recessive allele to show phenotype

54
Q

Fill out genotypes

A

I – ned to be Aa because both need an a to give II3

II3 = aa because affected

II3 and II4 – need Aa to give a to IV2

III1 – if heterozyguous need to get a from mom bvecayse II1 is AA BUT II2 is not affected so she has to be Aa

***Can determine partial genotype – III1 is not affacted so is A_ and we know needs an A but we don’t knwo if mom gave A or a

***Assume that anyone coming in is AA because rare trait – safe to assume that non-relatives coming in are not carriers –> they are AA

55
Q

Example Autosomal Dominenant disorders

A

1 – Achyndroplasia – skelatal disorder causing dwrafism
2 – Huntingtons – nerodegenerative disease
3. Marfan syndrome – Connected tissue disorder

56
Q

Fill out genotypes

A

For dominenet – since it is rare you can assume that am affected individual that has unknown genotype is heterozygous (unlikeley that both parents could give them allele) – like I2

57
Q

Example Sex linked traits

A
  1. Red green color blindness
  2. Duchene muscular distrophy
  3. hemophelia – blook clotting disorder

***Traits on sex chromsomes

58
Q

Fill out the genotypes

A

II4 – can assume XX because it is rare and she is not related = can assume she is not a carrier

II2 – has an affected son but she is not affected = needs to be a carrier

IV2/3 – Need to be Xr because the dad is XrY and he gives them one X chromsome

59
Q

Look at page 8 of notes

A
60
Q

X-linked dominant Disease

A

Very rare – they are often are lethal before birth in males = only seen in females

  1. Aicardi syndrome (brain defect)
  2. Incontinetia Pigement – skin lesions
  3. X-linked Rickets – Bone lesions
61
Q

Fill out genotypes

A

Notes:
- Parents that are not carriers don’t have trait = no affected kids

- Unaffected parents have unaffected kids

III7 – is not affected = got not affected X from mom

62
Q

Y-linked disorders

A

Overall – easy to follow because the trait only affects individuals with Y chromsomes = only affects males
- Traits appear only in males
- Every generation – all males receive the trait causing alleles

Examples:
1. Certain alleles of the SRY gene (sex determination)
2. Certain alleles of SOX2 (male pattern baldness)

63
Q

Mitocondria (overall)

A

Mitocondria = make structural network in cell that produces energy – mitocondria are the powerhouse of the cell

64
Q

Most organisms inheritance of mtDNA

A

Usually it is uniparental – only get it from one parent

***In mammals inheritance of mtDNA = materall –> egg has all mtDNA

65
Q

mtDNA trend

A

because mtDNA = tramistted through egg – THEN if you have affected female = passes the trait to ALL kids
- Affected females pass affected mtDNA tp all kids but affected males do not pass down mtDNA to offspring = affected males do not have affected kids

66
Q

What leads to incomplete penetrance in mtDNA

A

Unequal division

67
Q

Why is mtDNA inheritnace not straight foward

A

Because offspring can receive different amounts of the different types of mtDNA that are present
- Might have enough of mutant to show phenotype or might not have enough to shwo phenotype

68
Q

Example of a typical mtDNA inheritance

A

Have a daughter that passes mtDNA to son and daughter who weren’t affected but her grandchildren are affected
- Kids can be affected but the mom is not affected

***mtDNa shows incomplete penetrance were not every individual that has the mutant mtDNA has the trait

69
Q

Example mtDNA disease

A
  1. Mitocondrial myopathy muscle loss
  2. Lebers heriditary optic nueropathy – loss of eyesight
  3. Leighs syndrome – encepalopathy
  4. MERF syndroome – epilepsy
  5. mtDNA depletion syndrome

BIOL332 (25 decks)

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