Complex Inheritance Flashcards by Guy Ben Arie | Brainscape

Q

Most of the human traits are: (4 descriptions in genetics)

A

Polygenic, Continuous, Additive effects and Multifactorial

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Q

What does Polygenic means?

A

Polygenic- caused by many genes

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Q

What does Continuous (in genetics..) means?

A

Continuous- quantitative traits

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Q

What does Additive effects means?

A

not dominant or recessive

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Q

What does Multifactorial means?

A

Multifactorial - environmental factors also involve

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Q

Examples for Complex inheritances traits:

A

Examples for Complex inheritances traits:

Skin color, weight, height, glucose in blood, cholesterol in blood, BP, shoe size, IQ etc.

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Q

Characteristics of multifactorial traits (diseases):

What kind of Pattern - Mendelian or not?

A

Characteristics of multifactorial traits (diseases):

No Mendelian pattern of inheritance

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Q

Characteristics of multifactorial traits (diseases):

What increases risk of diseases - Many or Few Children?

A

Characteristics of multifactorial traits (diseases):

Recurrence risk increases with the number of affected children in a family (because same lifestyle)

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Q

Characteristics of multifactorial traits (diseases):

What increases risk of diseases - Relative that is severely or moderately affected?

A

Characteristics of multifactorial traits (diseases):

There is a higher recurrence risk if the relative is more severely affected

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Q

Characteristics of multifactorial traits (diseases):

What increases risk of diseases - Insest or Normal realtionship?

A

Characteristics of multifactorial traits (diseases):

Marriage of relative moderately increases the risk (not significant risk)

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Q

Characteristics of multifactorial traits (diseases):

Does the disease affect both/one/one more than other gender?

A

Characteristics of multifactorial traits (diseases):

Disease occurs more frequently in one gender, but is not sex-linked / -limited (one more than other)

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Q

Characteristics of multifactorial traits (diseases):

Concordance rate in monozygotic and dizygotic twins contradicts or falls in line with Mendelian proportions

A

Characteristics of multifactorial traits (diseases):

Concordance rate in monozygotic and dizygotic twins CONTRADICTS Mendelian proportions

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Q

Characteristics of multifactorial traits (diseases):

Does environmental factors - (+)/(-)/both/none influence the disease?

A

Characteristics of multifactorial traits (diseases):

Environmental influence can increase or decrease the risk of the disease

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Q

Characteristics of multifactorial traits (diseases):

Do the diseases occurs frequently in ethnic groups or is it worldwide?

A

Characteristics of multifactorial traits (diseases):

The disease occurs more frequently in a specific ethnic group

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Q

Methods applied in complex inheritance- used in identification of genetic (environmental) background:
Familial aggregation

A

Familial aggregation:

Frequency of the disease in relative / siblings compared to frequency in population

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Q

Methods applied in complex inheritance- used in identification of genetic (environmental) background:
λs =

A

λs =Frequency of the disease in relative / siblings compared to frequency in population

(Familial aggregation)

Q

Methods applied in complex inheritance- used in identification of genetic (environmental) background:
λs > 1
What does that mean?

A

λs > 1

High genetic influence

Q

Methods applied in complex inheritance- used in identification of genetic (environmental) background:
λs < 1
What does that mean?

A

λs < 1

Low genetic influence

Q

Methods applied in complex inheritance- used in identification of genetic (environmental) background:
Twin studies - What is Concordance?

A

Twin studies - Concordance:

both of the twins have the trait

Q

Methods applied in complex inheritance- used in identification of genetic (environmental) background:
Twin studies - What is Discordance?

A

Twin studies - Discordance

only one of the twins have the trait

Q

Factors which make the determination of genetic background of the complex disease difficult: (4)

A

Genetic heterogeneity (locus or allelic)
Phenocopy
Pleiotropy
Incomplete penetrance

Q

What is a Haplotype?

A

Haplotype:

a set of genetic determinants located on a single chromosome.

Q

What is Linkage disequilibrium (LD)?

A

Linkage disequilibrium (LD):
the non-random association of alleles at two or more loci that may or may not be on the same chromosome.

Q

What is Linkage disequilibrium (LD) used for?

A

It is used in population genetics for the calculation of the chance of co-inheritance of two alleles.
In other words- it is the occurrence of some combinations of alleles in a population more or less often than would be expected from a random formation of haplotypes from alleles based on their frequencies.