19 Genetics & Development 3 Flashcards

1
Q

Interpret a pedigree chart: label the image

A

see image

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2
Q

Four Rules of the Pedigree chart:
1. AD =
2. If disorder is dominant what can be inferred about parents?
3. Recessive disorder - parents?
4. X-linked?

A
  1. AD = autosomal dominant // Disease appears in both sexes equally
  2. If disorder is dominant = one of the parents must have the disorder
  3. Recessive disorder - neither parent has to have disorder because both can be heterozygous
  4. X-linked - Allele located only on X chromosome = recessive by definition
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3
Q

Looking at a pedigree chart, how could you determine if a disorder is X-linked or autosomal?

A
  • If most males in the pedigree are affected = X-linked
  • If 1/2 ratio (50/50) between M and F = Autosomal
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4
Q

In the image is the disorder:
A. Autosomal Dominant
B. Autosomal Recessive
C. X-linked?

A

Autosomal recessive

Recessive disorder - neither parent has to have disorder because both can be heterozygous

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5
Q

In the image is the disorder:
A. Autosomal Dominant
B. Autosomal Recessive
C. X-linked?

A

Autosomal Dominant

AD = autosomal dominant // Disease appears in both sexes equally
2. If disorder is dominant = one of the parents must have the disorder

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6
Q

In the image is the disorder:
A. Autosomal Dominant
B. Autosomal Recessive
C. X-linked?

A

X-linked

Allele located only on X chromosome = recessive by definition
- generally recessive in females - affects males at higher rate

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7
Q

Differentiate between
- autosomal dominant
- autosomal recessive,
- X-linked,
- Y-linked and
- mitochondrial inheritance patterns

A
  • autosomal dominant: manifested ikn the heterozygous state (at least one parent is usually affected) // affects both males and females
  • autosomal recessive: both alleles at given locus are mutated // trait doesnt usually affect parents // 25% risk for each child
  • X-linked: generally recessive in females - affects males at higher rate
  • Y-linked - only affects males (father -> son)
  • mitochondrial inheritance patterns: maternal inheritance (ova contain numberous mito. within abundant cytoplasm&raquo_space; spermatozoa)
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8
Q

Differentiate between
- autosomal dominant
- autosomal recessive
- X-linked,
- Y-linked and
- mitochondrial inheritance patterns

A
  • autosomal dominant: manifested ikn the heterozygous state (at least one parent is usually affected) // affects both males and females
  • autosomal recessive: both alleles at given locus are mutated // trait doesnt usually affect parents // 25% risk for each child
  • X-linked: generally recessive in females - affects males at higher rate
  • Y-linked - only affects males (father -> son)
  • mitochondrial inheritance patterns: maternal inheritance (ova contain numberous mito. within abundant cytoplasm&raquo_space; spermatozoa)
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9
Q

Differentiate between
- autosomal dominant
- autosomal recessive
- X-linked,
- Y-linked and
- mitochondrial inheritance patterns

A
  • autosomal dominant: manifested ikn the heterozygous state (at least one parent is usually affected) // affects both males and females
  • autosomal recessive: both alleles at given locus are mutated // trait doesnt usually affect parents // 25% risk for each child
  • X-linked: generally recessive in females - affects males at higher rate
  • Y-linked - only affects males (father -> son)
  • mitochondrial inheritance patterns: maternal inheritance (ova contain numberous mito. within abundant cytoplasm&raquo_space; spermatozoa)
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10
Q

Differentiate between
- autosomal dominant
- autosomal recessive
- X-linked,
- Y-linked and
- mitochondrial inheritance patterns

A
  • autosomal dominant: manifested ikn the heterozygous state (at least one parent is usually affected) // affects both males and females
  • autosomal recessive: both alleles at given locus are mutated // trait doesnt usually affect parents // 25% risk for each child
  • X-linked: generally recessive in females - affects males at higher rate
  • Y-linked - only affects males (father -> son)
  • mitochondrial inheritance patterns: maternal inheritance (ova contain numberous mito. within abundant cytoplasm&raquo_space; spermatozoa)
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11
Q

Differentiate between
- autosomal dominant
- autosomal recessive
- X-linked,
- Y-linked and
- mitochondrial inheritance patterns

A
  • autosomal dominant: manifested ikn the heterozygous state (at least one parent is usually affected) // affects both males and females
  • autosomal recessive: both alleles at given locus are mutated // trait doesnt usually affect parents // 25% risk for each child
  • X-linked: generally recessive in females - affects males at higher rate
  • Y-linked - only affects males (father -> son)
  • mitochondrial inheritance patterns: maternal inheritance (ova contain numberous mito. within abundant cytoplasm&raquo_space; spermatozoa)
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12
Q

What is Cystic Fibrosis (CF)
- (?) disorder of (?)
- affects (?) in (?) glands and in the (?) lining of the (?), (?) and (?) tracts
- Abnormally (?) secretions
- Complications such as (?), (?) insufficiency, (?), (?), (?), (?), (?)

A

Autosomal recessive transmission
- inherited disorder of ion transport
- affects fluid secretion in exocrine glands and in the epithelial lining of the respiratory, gastrointestinal and reproductive tracts
- Abnormally viscous (thick) secretions - obstruct organ passages
- Complications such as chronic lung disease secondary to recurrent infections, pancreatic insufficiency, steatorrhea, malnutrition, hepatic cirrhosis, intestinal obstruction, male infertility

steatorrhea is an increase in fat excretion in the stools.

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13
Q

Describe how mutations in the CFTR gene manifests as Cystic Fibrosis
- 6 possible CFTR defects:

A

Autosomal Recessive pattern of inheritance
1. No funtional CFTR protein = nonsense; frameshift; canonical splice
2. CFTR trafficking defect: Missense; Amino acid deletion
3. Defective channel regulation: Missense; AA change
4. Decreased channel conductance: Missense; aa change
5. Reduced CFTR synthesis: splicing defect; missense
6. Decreased CFTR stability: Missense; aa change

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14
Q

Genetic and Environmental modifiers of CF?

A
  • Polymorphisms in genes whose products modulate neutrophil funtion in response to bacterial infections
    Modifier loci for severity of pulmonary disease in CF
    eg Mannose binding lectin 2 (MBL2) // transforming growth factors B1 (TGF-B1) // interferon-related development of regulator 1 (IFRD1)
  • Bacteria (pseudomonas aeruginosa) can colonize the lower respiratory tract; concurrent viral infections predispose to such colonization
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15
Q

Define trinucleotide repeat disorder

A

Trinucleotide repeat disorders: consist of a group of human diseases, which are a result of an abnormal expansion of repetitive sequences and primarily affect the nervous system. These occur during various stages of human development

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16
Q

Define multifactorial inheritance
provide examples

A

Multifactorial inheritance is when more than 1 factor causes a trait or health problem, such as a birth defect or chronic illness. Genes can be a factor, but other things that aren’t genes can play a part, too. These may include: Nutrition. Lifestyle
Examples of multifactorial traits and diseases include: height, neural tube defects, and hip dysplasia.
- Type 1 Diabetes

17
Q

What are SNPs?

A

SNPs (Single nucleotide polymorphisms): DNA sequence variation occurring within a population in which G, A, T, C of the genome differ between members of the biological species or paired chromosomes
- the most common type of genetic variation among people.
- Each SNP represents a difference in a single DNA building block, called a nucleotide.

18
Q

What are STRs?

A

Short Tandem Repeats
- Dinucleotides (CA)n (n=10-60) distributed throughout the genome
- short repeated sequences of DNA (2–6 bp) that account for approximately 3% of the human genome

19
Q

What are CNVs?

A

Copy number variations
- DNA variation occurring in a cell with an abnormal number of copies of one or more sections of the DNA
- a circumstance in which the number of copies of a specific segment of DNA varies among different individuals’ genomes

20
Q

Four diseases stemming from trinucleotide repeat mutations:

A
  1. Fragile-X syndrome
  2. Fragile-X tremor ataxia
  3. Friedreich ataxia
  4. Huntington disease
21
Q

What is genomic imprinting?
Maternal/Paternal imprinting?

A

Genomic imprinting is the process by which only one copy of a gene in an individual (either from their mother or their father) is expressed, while the other copy is suppressed
Maternal imprinting: transcriptional silencing of maternal allele
Paternal imprinting: paternal allele is inactivated

22
Q

What is hirschsprung disease?

A

Failure of ganglion cells to migrate to the wall of the colon resulting from mutation in the receptor tyrosine kinase
1/5000 live births
- Polygenic; >10 dif genes and 5 loci
-

23
Q

Huntington Disease:
- transmission?
- Mutation?

A

Huntington disease:
- Panethnic, autosomal dominant, progressive neurodegenerative disorder
- Gene product, huntingtin, is ubiquitously expressed (function unknown)
- Normal HD alleles 10-26 CAG repeats; mutants have >36
- Instability and expansion of CAG repeats results in progressively earlier ages of onset with succedding generations (anticipation)
- Expansion of huntingtin polyglutamine tract appears to confer a deleterious novel property
- SEVERE atrophy of neostriatum = hallmark of HD
- Neuronal dysfunction, generalized brain atrophy neuronal death

24
Q

What is gonadal mosaicism?

A

Gametes have mutated cells