Lecture 12: Principles of Genetic Inheritance Flashcards

1
Q

What is the term for a disease allele on the X chromosome in males?

A

hemizygous

  • females rarely affects, if homozygous: lyonization occurs in development (X-inactivated)
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2
Q

Mitochondrial DNA and mutations

A
  • mitochondria inherited exclusively through maternal line

- mutation rate 10x higher than nDNA (no DNA repair mechanisms)

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3
Q

Leber’s Hereditary Optic Neuropathy (LHON)

A
  • degradation of retinal ganglion cells
  • affects NADH dehydrogenase
  • acute or subacute loss of central vision
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4
Q

Myoclonic Epilepsy and Ragged Red Fibers (MERRF)

A
  • mutations in gene encoding tRNA for lysine
  • disrupts cytochrome-c oxidase
  • ataxia and seizures, affects muscles and nerves
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5
Q

Mitochondrial Encephalomopathy, Lactic Acidosis, Stroke-like episodes (MELAS)

A
  • most common maternal inherited mito disease
  • affects brain, nervous system, muscles
  • stroke/dementia
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6
Q

Polyploidy vs Aneuploidy

A

Poly: cells have complete set of extra chromosomes

Aneuploidy: missing/have additional individual chromosome

NONDYSJUNCTION

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7
Q

Uniparental disomy

A
  • person gets two copies of chromosome from one parent and none from the other parent
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8
Q

Genomic Imprinting

A
  • essentially gene silencing (methylation 5’ gene region)

- germ cells: imprints are reset at each generation (meiosis –> erased and new ones set)

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9
Q

Inversion, Deletion, Duplication, Translocation

A
  • inversion: DNA segment in reverse orientation
  • deletion: segment lost
  • duplication segment copied, gene amplification
  • translocation: two different chromosomes exchange DNA segments
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10
Q

Reciprocal vs Robertson Translocation

A
  • Reciprocal: nonhomologous material exchange

- Robertsonian: long arm of acrocentric chromosome combined, short arm lost

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11
Q

Turner Syndrome

A

Karyotype: 45, XO

  • monosomy X, no Y chromosome
  • premature ovarian function, no puberty, infertile, webbed neck, CV defects
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12
Q

Prader Willi and Angelman Syndromes

A
  • deletion of chromosome 15 region

Paternal: PW
- short stature, small hands/feet, obese, uncontrolled eating

Maternal: Angelman
- intellectual disability, seizures, ataxic gait

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13
Q

Klinefelter Syndrome

A

Karyotype: 47, XXY

  • primary hypogonadism, small/undescended testies, infertility, tall
  • variability in X numbers increase symptoms
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14
Q

Downs Syndrome

A

Karyotype: 47, XX+21 (Trisomy 21)

  • most common (associated w/inc. maternal age)
  • cardiac defects, duodenal atresia
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15
Q

Edwards Syndrome

A

Karyotype: 47, XX+18 (Trisomy 18)

  • 95% die in utero (<10% live to 1 yo)
  • microencephaly, small mouth/jaw, cleft lip/palate, overlapped fingers
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16
Q

Patau Syndrome

A

Karyotype: 47, XX+13 (Trisomy 13)

  • closely spaced/absent eyes, cleft lip/palate, clenched hands and polydactyl
17
Q

Locus Heterogeneity

A
  • only one locus needed for phenotype to manifest
  • single disorder caused by mutations in genes at different loci
    ex: osteogenesis imperfecta
18
Q

Hardy-Weinberg Equation

A

p^2 +2pq + q^2 = 1

  • shows relationship between gene frequency and genotype frequency
19
Q

Autosomal Inheritance Patterns

A

Dominant: vertical transmissions, lack of skipped gens

Recessive: clustering of disease among siblings, disease not usually seen among parents or ancestors

CONSANGUINITY (Cousin Love)