Chapter 1: Intro to Mendelian Genetics and mtDNA non-mendelian genetics Flashcards Preview

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Flashcards in Chapter 1: Intro to Mendelian Genetics and mtDNA non-mendelian genetics Deck (23):
1

teratogens

agent or factor that causes embryonic malfunction

2

allele

particular copy of a gene on a chromosome

3

constitutional/congenital

present at birth

4

mosaic

two or more cell lines in one person (e.g. tumor cells)

arisen from the same parent cells

5

chimera

mix of cells from two individuals

6

monozygotic twins

identical twins

7

dizygotic twins

fraternal twins

8

consanguinity

individuals descended from a common ancestor

second cousins or closer

9

gene segregation

U... unit inheritance
S... segregation
A... assortment

10

Autosomal Dominant
- definition
- expression in population
- transmittance
- variance
- penetrance
- de novo mutation locations
- how to check on pedigree

- only one copy of gene needed to show phenotype
- 50% M 50% F
- vertical transmittance
- variable expression
- incomplete penetrance (observed in BRCA gene)
- de novo mutations occur in hotspots of genome, occurrence can increase with advancing paternal age
- Male to Male transmission observed

11

Marfan Syndrome

Systematic disorder of connective tissue
Autosomal dominant
Variable Expressivity

12

Achondroplasia

Skeletal dysplasia (Tyrion)
Autosomal dominant (usually Aa, AA is lethal)

13

Autosomal Recessive
- definition
- expression in population
- characteristic predisposition
- transmittance
- variance
- penetrance
- effect of consanguinity
- how to check on pedigree

- needs two copies of gene to express phenotype
- 50% M 50% F
- may have ethnic predisposition (sickle cell and CF)
- transmittance not usually observed, may have no family history
- less variance
- full penetrance
- consanguinity can increase the probability of
- no family history, dot on the map (only one generation affected)

14

X - linked Recessive
- definition
- expression in population
- transmittance
- penetrance
- how to check on pedigree

- F: both X mutated || M: singular X mutated
- much more common in M than F (though F is observed)
- can be inherited through several generations, male to male transmittance never observed
- all daughters of affected M are carriers
- F carriers may have mild expression
- only M, no M to M transmission

15

X - linked Recessive Female expression
- reasons why females may show phenotype/expression

- 45,X karyotype; Turner's syndrome
- Lyonization which results in skewed X inactivation
- M & F are both carriers 1/4 chance

16

X - linked Dominant
- definition
- expression in population
- transmittance
- penetrance
- how to check on pedigree

- F: only one X mutated || M: singular X mutated
- much more common in F than M (though M is observed, often lethal)
- Male to Male transmission is not observed
- daughters of affected M will always be affected
- affected M gives to all daughters
- extremely rare!!!

17

Hemophilia
- symptom/cause
- genetic factor

- bleeding disorder caused by deficiency factor VIII or IX
- X linked recessive

18

Duchenne Muscular Dystrophy
- symptom/cause
- genetic factor

- progressive muscular disease
- X linked recessive

19

Incontinentia pigmenti

- Disorder of hair, skin, teeth, etc. (notable by incongruous pigmented skin)
- X linked dominant

20

mitochondria basics

powerhouse of the cell
has its own mtDNA

21

mitochondrial inheritance
- MELAS?
- transmission
- % mtDNA in child
- threshold
- age effect
- parts most likely affected

- mutated mtDNA
- Mitochondrial Encephalomyopathy, Lactic Acidosis, Stroke-like episodes
- maternal transmission bc mother gives mtDNA to child
- % of abnormal mtDNA can change due to chance variation, or selective advantage
- certain amount of mutated mtDNA is allowed before phenotype is shown
- mt function decreases with age due to free radicals, increased mutation rate, reduction/loss in function
- tissue with highly metabolic needs most likely affected

22

heteroplasmy vs. homoplasmy

- mixture of normal/abnormal mtDNA
- all of normal or abnormal mtDNA

23

mtDNA MELAS treatment

- three parent IVF: transport healthy mtDNA into egg
- nuclear transfer: transport nucleus into healthy egg (without nucleus)