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

Question 1

teratogens

Answer 1

agent or factor that causes embryonic malfunction

Question 2

allele

Answer 2

particular copy of a gene on a chromosome

Question 3

constitutional/congenital

Answer 3

present at birth

Question 4

mosaic

Answer 4

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

arisen from the same parent cells

Question 5

chimera

Answer 5

mix of cells from two individuals

Question 6

monozygotic twins

Answer 6

identical twins

Question 7

dizygotic twins

Answer 7

fraternal twins

Question 8

consanguinity

Answer 8

individuals descended from a common ancestor

second cousins or closer

Question 9

gene segregation

Answer 9

U… unit inheritance
S… segregation
A… assortment

Question 10

Autosomal Dominant

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

Answer 10

• 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

Question 11

Marfan Syndrome

Answer 11

Systematic disorder of connective tissue
Autosomal dominant
Variable Expressivity

Question 12

Achondroplasia

Answer 12

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

Question 13

Autosomal Recessive

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

Answer 13

• 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)

Question 14

X - linked Recessive

• definition
• expression in population
• transmittance
• penetrance
• how to check on pedigree

Answer 14

• 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

Question 15

X - linked Recessive Female expression

- reasons why females may show phenotype/expression

Answer 15

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

Question 16

X - linked Dominant

• definition
• expression in population
• transmittance
• penetrance
• how to check on pedigree

Answer 16

• 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!!!

Question 17

Hemophilia

• symptom/cause
• genetic factor

Answer 17

• bleeding disorder caused by deficiency factor VIII or IX

- X linked recessive

Question 18

Duchenne Muscular Dystrophy

• symptom/cause
• genetic factor

Answer 18

• progressive muscular disease

- X linked recessive

Question 19

Incontinentia pigmenti

Answer 19

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

Question 20

mitochondria basics

Answer 20

powerhouse of the cell

has its own mtDNA

Question 21

mitochondrial inheritance

• MELAS?
• transmission
• % mtDNA in child
• threshold
• age effect
• parts most likely affected

Answer 21

• 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

Question 22

heteroplasmy vs. homoplasmy

Answer 22

• mixture of normal/abnormal mtDNA

- all of normal or abnormal mtDNA

Question 23

mtDNA MELAS treatment

Answer 23

• three parent IVF: transport healthy mtDNA into egg

- nuclear transfer: transport nucleus into healthy egg (without nucleus)