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Genetic Condtions > Genetics Definitions/Characteristics > Flashcards

Genetics Definitions/Characteristics Flashcards

1
Q

SNV

A

Single Nucleotide Variation–an individual’s genetic information has a point mutation in it

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2
Q

SNP

A

Single Nucleotide Polymorphism–a point mutation in a gene has been identified in a population

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3
Q

Types of Gene Variation

A

1) SNP/SNV
2) Insertions and deletions
3) Structural changes (inversions, translocations)
4) Copy number variations (gene duplication)

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4
Q

Types of Repetitive Element Variations

A

1) Tandem-adjacent

2) Interspersed repetitive elements

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5
Q

Types of Tandem-Adjacent variations and roles

A

1) Satellite (appear in telomeres, centromeres. 100+bp repeats)
2) Variable number repeats (micro/10-60), highly variable in population. Appears in forensics
3) Short tandem repeats (mini 2-10 bp), seem to be involved in gene expression

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6
Q

Types of interspersed elements

A

1) LINES
2) SINES
3) DNA transposons
4) Retroviral like transposons

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7
Q

Difference between a mutation and a polymorphism

A

Polymorphisms require about 1% of the population to be affected by a conditions. Mutations often affect the phenotype negatively.

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8
Q

Mechanisms of mutation

A

1) Loss of function (gene off)
2) Gain of function (gene can’t go off)
3) Acquisition of a property
4) Dominant negative (a negative damages normal gene product)
5) Ectopic function

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9
Q

Difference between a major and minor malformation

A

Major malformations have cosmetic, surgical, and medical effects.
Minor malformations may have cosmetic effects but are not indicative of an underlying condition.

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10
Q

Definition of a syndrome

A

A set of physical/mental manifestations that can be traced to one etiology

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11
Q

Definition of aneuploidy

A

A gain or loss of a chromosome

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12
Q

Causes of aneuploidy

A

1) Meiotic Nondisjunction (parental)

2) Mitotic Nondisjunction (mosaic)

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13
Q

Holoprosencephaly

A

Failure of the brain to bilobate

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14
Q

Balanced translocation

A

A reciprocal shift in genetic material from one location to another without a phenotypic effect

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15
Q

Robertsonian translocation

A

The fusion of two acrocentric chromosomes around a centromere

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16
Q

Locations where a centromere can be found

A

Metacentric–the middle of the chromosome
Submetacentric–near the middle of the chromosome
Acrocentric–near the end of the chromosome

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17
Q

Unbalanced translocation

A

An inherited shift in genetic material that induces a phenotypic effect in the offspring

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18
Q

Isochromosomes

A

Robertsonian translocations that occur with two copies of the same chromosome

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19
Q

Paracentric Inversion

A

Inversion of genetic information that happens on the same side of the centromere at the original copy

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20
Q

Pericentric inversion

A

Inversion of genetic information that happens on the opposite side of the centromere of the original copy

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21
Q

Types of Genetic Testing

  • length of detectable DNA
  • advantages/disadvantages
A

1) Karyotyping, can see up to 8000 MBP of DNA, measures largescale genomic changes, less specific for certain sequences
2) FISH can detect ranges of 100-300 kBP of DNA, measures deletions, duplications
3) CMA can detect ranges of 1-5 KBP of DNA or RNA, also can measure deletions and duplications, also can look at gene expressivity (if using RNA). Cannot look at rearrangements of DNA

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22
Q

Penetrance

A

The extent to which a dominant allele is expressed in a population
–If 100% penetrance, then condition considered completely penetrant

23
Q

Mendel’s First Two Laws

A

1) Two members of a factor pair segregate independently

2) Factors for different traits segregate differently from one another (except linkage)

24
Q

Characteristics of Autosomal Dominant Conditions

A

1) 1 mutant allele necessary to cause a change in a condition
2) Equally applies to both sexes
3) Affects multiple generations in a pedigree
4) The heterozygous person has a 50% recurrence risk

25
Q

Variable expressivity

A

Some conditions will show symptoms more forcefully in some individuals than others

26
Q

Heterogeneity

A

A condition has more than one cause

27
Q

Homozygous lethal affect

A

Many dominant disorders (except Huntington’s disease) are fatal if the patient has a homozygous genotype

28
Q

Allelic heterogeneity

A

Multiple mutations in one allele can cause a disease

29
Q

Locus heterogeneity

A

Multiple mutations in different alleles can manifest as the same disease (usually seen in protein complexes)

30
Q

Autosomal recessive characteristics

A
  • requires 2 mutant alleles to cause disease
  • affects sexes equally
  • few generations affected; may disappear and reappear
  • Heterozygotes have normal phenotypes
  • Siblings of affected patients have a 2/3 chance of being carriers
  • recurrence risk is 25%
  • most metabolic problems are inherited this way;
31
Q

Consanguinity

A

Interrelatednness in a couple; genetically higher risk to see very rare disorders

32
Q

Factors that affect allele frequency in humans

A
  • Drift
  • Migration
  • Non-random mating
33
Q

Founder Effect

A

A new population forms and poorly samples from society as a whole and a once rare allele becomes more common

34
Q

Bottleneck

A

Some sort of disaster destroys a large population and happens to leave a person with a recessive allele alive

35
Q

Selection

A

Specific traits are either deliberately relevant to maintain (artificial) or a phenotype has a natural predilection to survive a series of events (natural)

36
Q

Heterozygote advantage

A

Some factor in the recessive allele confers a benefit to a generally normal phenotype to be heterozygous instead of homozygous dominant.

37
Q

Characteristics of X-dominant

A

Differential expression in males and females
Usually severely affected or lethal to males
Females variably affected
Ratio of males to females is usually 1:2 (especially if non-fatal condition)

38
Q

Haldane’s Law

A

A mom has a 2/3 risk of being a carrier if she produces male children with an X-linked disease with low fitness

39
Q

Characteristics of X-recessive

A
  • Males affected, healthy carrier females common
    • No male-to-male transmission
    • All daughters of affected males are obligate carriers at minimum
40
Q

X-inactivation

A

Females and Kleinfelter males randomly shut off one of the X chromosomes early in cell fate; the process cannot be reversed. Thus women are all X mosaics and may be symptomatic if their mosaic has a higher incidence of a disease state

41
Q

Genomic Imprinting

A

Genes are preferentially expressed from one parent over another. About 80 genes exist that demonstrate imprinting and most are developmental in nature

42
Q

Anticipation

A

A progressive worsening of a disease state over several generations that is noted in conditions affiliated with DNA repeats

43
Q

Heteroplasmy versus homoplasmy

A

Mitochondria with a certain genetic makeup can segregate differentially (hetero) or can segregate to the same daughter cell (homo) after mitosis

44
Q

Possible CNS symptoms with mitochondrial disease

A

a. CNS - hypotonia, ataxia, pyramidal signs, seizures, myoclonus, dementia, hearing loss

45
Q

Possible visual symptoms with mitochondrial disease

A

b. Eyes - retinitis pigmentosa, optic atrophy, cataract, nystagmus

46
Q

Possible muscle symptoms with mitochondrial disease

A

c. Muscle – weakness, exercise intolerance, red ragged fibers

47
Q

Possible cardiac symptoms with mitochondrial disease

A

d. Cardiac –cardiomyopathy, arrhythmia

48
Q

Possible liver symptoms with mitochondrial disease

A

e. Liver – hepatic failure

49
Q

Possible kidney symptoms with mitochondrial disease

A

f. Renal – renal tubular damage, Fanconi syndrome

50
Q

Possible GI symptoms with mitochondrial disease

A

g. GI dysfunction

51
Q

Possible blood related symptoms with mitochondrial disease

A

h. Hematologic – macrocytic anemia, pancytopenia

52
Q

Possible endocrine symptoms with mitochondrial disease

A

i. Endocrine – diabetes, short stature, exocrine pancreatic dysfunction

53
Q

Why are mutation rates in mitochondrial DNA higher?

A

No repair mechanisms

High exposure to free radicals

54
Q

Diagnostic evidence of a somaticism

A

Lines of Blaschko or segmental manifestations

Genetic Condtions (6 decks)

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