Patterns of Inheritance Flashcards

1
Q

locus

A

segment of DNA at a specific location

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2
Q

alleles

A

alternative variants of a gene

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3
Q

wild-type

A

single prevailing allele present in the majority of individuals (depends on population)

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4
Q

variants

A

mutants; gene other than WT

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5
Q

polymorphisms

A

variant alleles; may affect disease susceptibility

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6
Q

mutations

A

new genetic changes in a family or disease–cause mutant alleles

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7
Q

“non-gene” regions

A

non-protein coding RNAs lie in intergenic regions (within introns) –miRNA/lincRNA

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8
Q

genotype

A

entire set of alleles in a genotype or set of alleles at a specific locus

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9
Q

phenotype

A

observable expression of a genotype as a morphological, clinical, cellular, or biochemical trait

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10
Q

homozygous

A

individuals 2 alleles are FUNCTIONALLY identical at a specific locus

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11
Q

heterozygous

A

2 alleles are FUNCTIONALLY different

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12
Q

hemizygous

A

only 1 allele of a gene (men = X chromosome)

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13
Q

compound heterozygous

A

2 heterogoenous recessive alleles at a particular locus that cause genetic disease in a heterozygous state

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14
Q

pedigree

A

graphical representation of the family tree

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15
Q

kindred

A

extended family depicted in pedigree

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16
Q

proband

A

1st affected person brought to clinical attention (can be multiple)–analyze all other family members in relation to the proband

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17
Q

consultand

A

person who brings the phenotype to clinical attention (can be affected or unaffected individual)

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18
Q

first degree relatives

A

parents, siblings, offspring of proband

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19
Q

second degree relatives

A

grandparents, grandchildren, nieces, nephews, half-sibs

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20
Q

third degree relatives

A

first cousins

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21
Q

relative degree assignments

A

first, second, third, etc based on NUMBER OF STEPS in the pedigree between the two relatives

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22
Q

consanguineous

A

couples sharing 1+ ancestor in common; closely related (2nd cousins or closer)

23
Q

fitness

A

genetics term; refers to the measure of the impact of a condition/genotype on reproduction–defined by number of offspring who survive to reproductive age compared to a control group

24
Q

vertical transmission

A

transmission of a disease from one generation down to the next; implies family history of disease; excludes sporadic cases

25
Q

mosaicism

A

X-linked disorders; females randomly inactivate 1 X-chromosomes in each cell; phenotypic expression only in a subset of cells

26
Q

pure dominant

A

both homozygotes and heterozygotes show identical severity of phenotype

27
Q

semidominance

A

disease is more severe in homozygotes than heterozygotes–incomplete dominance–more common

28
Q

codominant

A

2 different allels are expressed together (ABO)

29
Q

penetrance

A

probability that a mutant gene will have any phenotypic expression

30
Q

reduced penetrance

A

When the percent of individuals with a mutant genotype demonstrating some disease phenotype is less than 100%

31
Q

expressivity

A

severity of expression of the phenotype in individuals with the same disease-causing genotype

32
Q

variable expressivity

A

when severity of a disease differs in people who have the same genotype

33
Q

congenital disease

A

phenotype recognized at birth

34
Q

late-adult onset

A

common way that severe autosomal dominant disease can continue to be passed on; don’t show up until after individual has reproduced (Huntington’s)

35
Q

allelic heterogenity

A

different alleles caused by different mutations of the SAME GENE result in varying disease phenotype; depending on severity of mutation, you get a range of different phenotypes

36
Q

locus heterogeneity

A

disease phenotype is caused by mutations in distinctly DIFFERENT GENES

37
Q

CFTR

A

allelic heterogeneity

38
Q

phenotypic heterogeneity

A

different mutations in SAME GENE cause completely DIFFERENT DISEASES

39
Q

RET gene mutation

A

phenotypic heterogeneity; causes dominantly inherited Hirschsprung and endocrine cancers

40
Q

autosomal recessive inheritance

A

occurs in mutant homozygotes or compound heterozygotes; no normal alleles

41
Q

sex influenced autosomal recessive inheritance

A

NOT X-linked recessive; both sexes develop the disease, one sex just has a higher frequency (increased penetrance)

42
Q

inbreeding

A

similar to consanguinity, but at the population level; describes individuals from a small pop. tending to choose their mates from within the same population (cultural, geographic, or religious influence)–>share gene alleles from ancestors (increasing homo. recessive disorders)

43
Q

likelihood of new mutations in autosomal dominant disorders rises dramatically with ____ of the parents

A

age

44
Q

Sex-limited phenotypes in autosomal dominant disorders

A

Different from X/Y-linked–can be mapped to an autosome and has direct father-son transmission; trait is seen ONLY in one sex; male-limited precocious puberty

45
Q

Precocious puberty

A

male-limited sex-limited autosomal dominant disorder

46
Q

Hemophilia A

A

X-linked disorder

47
Q

Purpose of X-inactivation

A

dosage compensation for expression of X-linked genes

48
Q

How do you determine if X-linked disorder is recessive or dominant?

A

Phenotype of heterozygous females; if consistently expressed in carriers = dominant

49
Q

Manifesting heterozygotes

A

X-linked recessive female carriers show some abnormalties in phenotype (severity depends on what the target tissue is)

50
Q

If an affected males’ daughters are all affected, but his sons are not, what is the inheritance pattern?

A

X-linked dominant inheritance (females have to have X from father–has to be mutant; males get normal Y)

51
Q

Only females exhibit disease; sons that exist are normal phenotype:

A

X-linked dominance with male lethality (living males received WT X from mother)

52
Q

Mutational Mosaicism

A

can occur from early development when clone of cells develops from a single mutation; these cells go on to form a tissue or part of tissue that is abnormal

53
Q

Mitochondrial Disorders

A

only inherited from mother; both male and female offspring have equal presentation of disease