Genetics

Front 1

Mendelian Traits:
Autosomal Dominant Inheritance

Back 1

Heterozygotes express the trait
Vertical pattern of transmission from one generation to the next
Transmitted by both sexes
Offspring are at 50% risk
Structural genes are often involved
New mutations are common ( point mut more common in sperm).

Front 2

Incomplete penetrance

Back 2

a trait that is not expressed in the phenotype of a gene carrier

Front 3

Complete penetrance

Back 3

genetic trait that is expressed in the phenotype

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Variable expression

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a genetic mutation associated with more than oe phenotype
Phenotypic variablity.

Front 5

Give an example of variable expression (phenotypic).

Back 5

The expression of Van der Woude syndrome varies within a family: some have cleft lip, some cleft palate, others lip pits
Interfamilial variation may be due to the effect of different mutations within the same gene.

Front 6

Mendelian Traits:Autosomal Recessive Inheritance

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Homozygotes express the trait
Horizontal pattern of transmission within a sibship.
Transmitted by both sexes
Offspring of carrier parents are at 25% risk
Functional genes are often involved
Ex. Sickle cell disease
Consanguinity is more common

Front 7

Incomplete penetrance

Back 7

a trait that is not expressed in the phenotype of a gene carrier

Front 8

Complete penetrance

Back 8

genetic trait that is expressed in the phenotype

Front 9

Variable expression

Back 9

a genetic mutation associated with more than oe phenotype
Phenotypic variablity.

Front 10

Give an example of variable expression (phenotypic).

Back 10

The expression of Van der Woude syndrome varies within a family: some have cleft lip, some cleft palate, others lip pits
Interfamilial variation may be due to the effect of different mutations within the same gene.

Front 11

Mendelian Traits:Autosomal Recessive Inheritance

Back 11

Homozygotes express the trait
Horizontal pattern of transmission within a sibship.
Transmitted by both sexes
Offspring of carrier parents are at 25% risk
Functional genes are often involved
Ex. Sickle cell disease
Consanguinity is more common

Front 12

X-linked recessive inheritance: When is it lethal?

Back 12

When transmitted by fmeales only- example Duchenne Muscular Dystrophy.

Front 13

X-linked recessive inheritance: When is it not lethal?

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WHen transmitted by both sexes- example color blindness

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Anticipation

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The phenotype becomes more severe or evident at a younger age of onset with each successive generation
Example: The triple repeat (The repeat number correlates to the severity of the disease, at meiosis can’t line up correctly).

Front 15

Give an example of anticipation be specific

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The premutation for Fragile X in a normal transmitting male expands during female meiosis in his unaffected daughter to a full mutation in her affected son.

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Parent of Origin Effect

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Parent of Origin effect - The phenotype varies depending on which parent transmits the abnormal allele

Front 17

How does Methylation affect gene products (parent of origin effect)?

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Methylation patterns differ in male and female meiosis: some genes are active only when inherited from one parent (imprinting)
Ex. Only the maternal copy of the Angelman syndrome gene is active; the paternal gene is inactive.

Front 18

Polygenic traits

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many genes each make a small contribution to the phenotype
Ex. Intelligence, height

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Multifactorial traits

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Few genes make a major contribution to the phenotype in a permissive environment
Ex. Spina Bifida, MTHFR and folate deficiency

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Mosaicism

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A mutation affects only some cells in the body with a variable phenotype
osteogenesis imperfecta Type II (lethal autosomal dominate trait)

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Specific Example of Chromosomal translation

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Down Syndrom due to familial translocation

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Specific example of maternal inheritance

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Mitochondrial genome is cytoplasmic so mitochondrial defects are passed down in the egg cytoplasm from the mother to all of her children

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Carrier Frequency

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Prevalence of an altered diease gene

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Founder Effect

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higher fequency of a specific gene mutation in a populaiton founded by a small ancestral group

Front 25

What percent of sibilings will be a carrier of CF of an affected brother/sister?

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66P of siblings will be a carrier of CF of an affected brother/sister.

Front 26

What do you use genome scanning techniques for?

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To search for chromosome aberrations (differences).

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What is CGH? (genetic testing)

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Comparative Genomic Hybridiation (CGH). Used to determine deletion or insertion.

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Start Codon

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AUG

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Why are splice site important?

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They tell the the intron will be cleaved out, if there is a mutation on an intron will get the wrong exons put to other aka wrong mRNA.

Front 30

Define: Polymorphism

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DNA changes that do NOT alter the protein function.

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Define: Mutation

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Change in normal base pair and ALTERS protein function.

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Missense Mutation

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Changes to a codon cause a another AA to be added.

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Nonsense

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Change AA codon to a STOP codon

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Frameshift

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insertion/deletion of base pairs cause a STOP codon downstream

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What part of blood do you use for DNA testing?

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WBC

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Linkage Analysis

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Looks for DNA markers near gene of interest. Need multiple family members DNA aalysis.

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ASO Hybridization

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Allele Specific Oligonucleotide Hybridization.
1) Amplify DNA
2) Add radiolabeled normal probes and known mutant DNA
3) Observe that the mutant matches up with one ( on paper dot mutatnt will match up with known)

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PCR

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Polymerase Chain Reaction (PCR). Use 2 primers amplify

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Single Strand Conformational Polymorphism (SSCP)

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Denature
Put in Gel
Look for difference in movement compaired to normal.
Checking shape!

Front 40

Heteroduplex Analysis (CSGE)

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Amplify
Denature
Single Strand
Cold
Re-nature (can see the extra nucleotides, due to genetic problem).
See that some bands are different on gel.

Front 41

DNA Sequencing

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Read Left to right and then top to bottom

Front 42

Protein Truncation Assay

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DNA --> RNA
RNA --> Protein
Protein put on gel.
See different mobility on getl for the truncated one!

Front 43

What is the major cause of morbidity and mortality in infants?

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Congenital anomalies