Patterns Of Inheritance I Flashcards

1
Q

Pleiotrophy

A

The mutation produces multiple distinct phenotype so that may or may not appear in a particular individual

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2
Q

Why are pedigrees useful

A

Is the trait heritable
Chromo location of cause genes
Risk to other family members

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3
Q

Proband

A

Isolated case of a genetic disorder involving a family member who draws attention to a pedigree

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4
Q

Index case

A

The clinically affected family member through whom attention is first drawn to a pedigree of particular interest to human genetics

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5
Q

Penetrance

A

The probability that a gene will have any phenotypic expression at all

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6
Q

Expressivity

A

The severity of expression of the phenotype

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7
Q

Pleiotropy

A

When an allele of a gene produces several phenotypic effects

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8
Q

Autosomal Dominant Inheritance Characteristics

A
  1. Multiple generations affected
  2. Males and females are equally affected
  3. Male to male transmission
  4. Each offspring has a 50/50 chance of being affected to unaffected
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9
Q

AD disorders that are homozygous are…

A

Lethal

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10
Q

Examples of AD diseases

A

Polycystic Kidney Disease
Defect in PKDI on 16p13
Onset when 40-50

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11
Q

Autosomal recessive characteristics

A

Parents can be unaffected

Equal expression in both sexes

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12
Q

Examples of AR inheritance diseases

A

Taysachs disease

Accumulation of gangliosides in neurons

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13
Q

PKU

A

AR disease involving mental retardation and can be averted with proper dietary considerations in a timely fashion

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14
Q

Consanguinity

A

Genetic relationship where individuals have at least one common ancestor in the preceding few generations

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15
Q

First Degree Relatives

A

50% of genes shared

Includes parents, siblings, and offspring

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16
Q

Second degree relatives

A

25% genes shared

Grandparents, aunts/uncles, grandchild, niece/nephew

17
Q

Third degree relatives

A

12.5 % genes shared

First cousins

18
Q

Isonymous marriage

A

Marriage between persons with the same surname

19
Q

X-linked recessive inheritance

A

Much higher incidence in males than females
All daughters if affected males will be carriers
Condition is never transmitted father to son

20
Q

What exceptions cause XR’s to be more severe

A

Extreme Lyonization

Turner Syndrome

21
Q

Examples of XR inheritance

A

Hemophilia A and DMD

22
Q

XD inheritance characteristics

A

Females should be affected twice as much as males

All daughters of affected males will be affected and none of the sons will

23
Q

XD disease examples

A

Ret Syndrome

Vitamin D resistant rickets

24
Q

Mitochondrial inheritance characteristics

A

-inheritance has maternal origin
-all offspring of an affected mother are at risk of being affected
All daughters of an affected mother are at risk of transmitting the disease

25
Q

Heteroplasmy

A

More than one type of mDNA is seen in the mitochondria of an individual

26
Q

Examples of mitochondrial diseases

A

LHON(bilateral vision loss)
KSS(retinal pigment degeneration)
MERRF

27
Q

Y linked inheritance

A

Only males are affected and one male to male transmission is seen