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HESP632 Final > Genetics > Flashcards

Genetics Flashcards

1
Q

What is a genome?

A
  • Complete set of genetic information, all the biologic information needed to build and maintain an organism
  • Comprises all of the organism’s DNA
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2
Q

What is an exome?

A
  • Protein coding portion of DNA

- ~1% of total genome

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3
Q

What is an intron?

A
  • Non-coding sections of a gene

- Important biologic functions

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4
Q

What is a nucleotide?

A
  • Nitrogen-containing base (A and G are purines; T and C are prymidines)
  • Sugar
  • Phosphate
  • Nucleotide strand forms a spiral (double helix)
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5
Q

What is DNA transcription?

A
  • mRNA takes coding to ribosomes where amino acids are formed
  • Each tri-nucleotide sequence = codon
  • 20 types of amino acids (each specified by codons)
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6
Q

What are amino acids?

A
  • Building blocks of proteins
  • Sequenced, linked to form proteins
  • Order of amino acids dictates protein shape and function
  • Proteins play a critical role in the body
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7
Q

What is a mutation?

A

-Change in a gene’s biochemical makeup, change at the DNA level

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8
Q

What is a mutagen?

A
  • A substance that causes a mutation

- EX: raidation

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9
Q

What is a mutant?

A

-An allele that differs from the mild type (normal or most common) allele, altering the phenotype

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10
Q

What is a spontaneous mutation?

A

-A genetic change resulting from the mispairing of bases during replication

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11
Q

What is a mutational hot spot?

A

-Most likely to happen when the nearby DNA is repetitive or symmetrical

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12
Q

What is a point mutation?

A

-Involving a single nucleotide in the DNA molecule

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13
Q

What is a missense mutation?

A
  • Change in a codon so that it codes for a different amino acid
  • EX of a point mutation
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14
Q

What is a nonsense mutation?

A
  • Changes a codon specifying an amino acid into a “stop” codon
  • Results in a shortened protein product
  • EX of a point mutation
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15
Q

What are deletion/insertion mutations?

A

-Involving >1 nucleotide

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16
Q

What is a frameshift mutation?

A

-Addition or deletion of bases that are not a multiple of 3 with disruption of the reading frame of the protein

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17
Q

What are examples of deletion/insertion mutations?

A
  • Frameshift mutation
  • Codon deletions and insertions
  • Expansion
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18
Q

What are the classifications of inheritance patterns?

A
  • Chromosomal abnormalities
  • Mendelian inheritance (mongenic)
  • Non-Mendelian inheritance (digenic)
19
Q

What are types of Non-Mendelian Inheritance?

A
  • Mitochondrial
  • Polygenic
  • Modifier gene
  • Multifactorial
20
Q

What are types of Mendelian Inheritance?

A
  • Autosomal dominant
  • Autosomal recessive
  • Sex-linked (X- or Y-linked)
21
Q

What is aneuploidy?

A
  • Abnormal # of chromosomes

- EX: sex chromosome aneuploidy, trisomy

22
Q

What are examples of chromosomal aberrations?

A
  • Aneuploidy
  • Translocations
  • Deletions
  • Contiguous gene syndromes
  • Isochomosomes
  • Inversions
23
Q

What is heterogeneity?

A
  • Several different genes result in one phenotype

- EX: deafness, blood clotting disorders

24
Q

What is phenocopy?

A
  • An environmental factor mimics a genetic condition and results in the same phenotype
  • EX: hair loss from chemotherapy, mimics alopecia
25
Q

What is pleiotropy?

A
  • One gene (or a pair of genes) causes multiple phenotypic effects in the body
  • EX: Marfan syndrome
26
Q

What is penetrance?

A
  • The percentage of individuals who possess a dominant gene and express it
  • Incompletely penetrant (not every individual who has the genotype displays the phenotype)
27
Q

What is variable expressivity?

A

-A genotype producing a phenotype that varies among individuals

28
Q

Describe X-linked recessive inheritance.

A
  • DFNX
  • M&raquo_space;> F
  • No father-to-son transmission
  • All daughters of a male with the trait will be carriers
  • Carrier females: 50% chance to have sons with the trait, 50% chance to have carrier daughters
  • Trait may be transmitted trough a series of carrier females
29
Q

What is mitochondrial inheritance?

A
  • Trait is passed through maternal line only
  • All offspring of a mother with the disorder will inherit the trait
  • No children of a father with the disorder will inherit the trait
  • M = F
  • Reduced penetrance, variable expressivity, and pleiotropy
30
Q

Describe the phenotype of nonsyndromic DFNA.

A
  • Less severe than DFNB
  • Postlingual > prelingual
  • Sometimes hard to differentiate form environmental factors and aging
  • Genetically heterogeneous
  • SNHL
  • Progressive
  • ~70 DFNA loci
  • 35+ genes have been identified (some loci have more than one genes)
  • EX: DFNA6/14
31
Q

Describe the phenotype of nonsyndromic DFNB.

A
  • ~56% of prelingual hereditary HL
  • Predominantly: prelingual SNHL, bilateral, severe-to-profound, stable, all frequencies
  • Tendency to partner with another deaf person
  • > 100 loci mapped
  • EX: GJB2
32
Q

What are some genetic approaches to understanding auditory function?

A
  • Gene regulation
  • Fluid homeostasis: gap junctions, ion channels, transporters
  • Junctional complex and tight junctions
  • Structural integrity
  • Synaptic transmission
33
Q

What are some examples of syndromic hereditary HL?

A
  • Alport syndrome
  • CHARGE
  • Branchio-oto-renal (BOR) syndrome
  • Stickler syndrome
  • Treacher Collins
34
Q

What are the clinical features of Alport syndrome?

A
  • Hematuria (blood in urine)
  • Nephritis with progressive renal failure
  • Eye abnormalities (i.e. cataracts)
  • Progressive SNHL with onset in late childhood to early adulthood
35
Q

What is the inheritance pattern for CHARGE?

A
  • Heterozygous mutations

- Genes: CHD7, SEMA3E

36
Q

What is the inheritance pattern for Alport syndrome?

A
  • X-linked
  • AR
  • AD
  • Genes: COL4A3, COL4A4, COL4A5
37
Q

What are the clinical features of branchio-oto-renal (BOR) syndrome?

A
  • SNHL, CHL, or MHL
  • Branchial pits, cysts, and/or fistulae
  • Renal dysplasia or aplasia
  • Malformed pinnae
  • Ear pits and/or tags
38
Q

What is the inheritance pattern for BOR syndrome?

A
  • AD

- Gene: EYA1

39
Q

What are the clinical features of Stickler syndrome Type I?

A
  • SNHL, occasionally CHL
  • Progressive myopia
  • Midface hypoplasia
  • Retinal detachment
  • Mitral valve prolapse
  • Degenerative joint disease
40
Q

What is the inheritance pattern for Stickler syndrome?

A
  • AD
  • Type I Gene: COL2A1
  • Type II Gene: COL11A1
  • Type III Gene: COL11A2
41
Q

What are the clinical features of Treacher Collins syndrome?

A
  • Malar hypoplasia
  • Malformed auricles
  • CHL
  • Ear tags
  • Downward slanting palpebral fissures
  • Lower lid coloboma
  • Mandibular hypoplasia
  • Macrostomia
42
Q

What is the inheritance pattern for Treacher Collins syndrome?

A
  • AD

- Gene: TCOF1

43
Q

What temporal bone lesions can be identified with CT scan.

A
  • EVA
  • Mondini dysplasia
  • Lateral canal dysplasia (CDH7)
  • Calcification of cochlea (CMV, meningitis)

HESP632 Final (7 decks)

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