Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MHG > Multifactorial Genetics > Flashcards

Multifactorial Genetics Flashcards

1
Q

What is the most common genetic condition and what is its incidence?

A

Multifactoral disorders affect 20-40% of people with genetic conditions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are some examples of multifactorial disorders and their incidence in population?

A
  • Oral clefts (1/500 - 1/1,500)
  • Neural tube defects (1/100 - 1/1000)
  • Congenital heart defects (1/100)
  • Diabetes (1/100)
  • Schozophrenia (1/100)
  • Hydrocephalus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the most common multifactorial condition found in newborns?

A

Congenital heart defects (1%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are some difficulties in understanding multifactorial genetics?

A
  • Inheritance of multifactorial conditions is more difficult to analyze
  • Genetic patterns are not clear cut in individuals families
  • Multifactorial conditions are difficult to replicate in animal studies due to environmental conditions
  • Separating the effects of genetics and the envrionment to study the conditions is hard
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Quantitative traits

A

Traits that can be measured with a number (i.e. weight, height, enzymatic BP, IQ)
- Inheritance of quantitative traits is multifactorially determined: caused by additive effects of genetics and environmental conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are some of the characteristics of inheritance patterns of multifactorial conditions?

A
  • Follow a bell shaped curve

- Additive effects of genetic and environmental factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Concordance

A

Means that both twins in a twin study are affected.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Twin Studies

A

One approach to solve the influence of genetics vs. environment. The frequency of concordance of monozygotic twins is compared with that of dizygotic twins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

In twin studies, what is the expected concordance rate in a pure genetic condition?

A

For monozygotic twins it is 100% and for dizygotic twins it is less than 100% and similar to the concordance rate among siblings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

In twin studies, what is the expected concordance rate in a pure environmental condition?

A

Concordance rates for monozygotic and dizygotic twins will be the same/very close

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

In twin studies, what is the expected concordance rate in a multifactorial condition?

A

In multifactorial conditions, the concordance rate of monozygotic twins is higher than dizygotic twins but not 100%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How is the effect of the environment on a genotype studied?

A

Monozygotic twins reared apart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the difficulties with twin studies?

A
  • Monozygotic twins are treated differently than dizygotic twins
  • Somatic mutations can occur during development leaving monozygotic twins not completely identical
  • Uterine environment for monozygotic twins may not be identical
  • Number of monozygotic twins reared apart is small
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Relative risk ratio

A

Lambda r = (prevalance of the disease in a relative “r” of an affected person)/(population prevalance of the disease)
- Compares the frequency of a disease within a family to the disease’s frequency in the general population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Heritability

A

Percentage of the population variation in a trait that is due to genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Heritability formula

A

H=2(cmz-cdz)
- cmz: concordance rate for monozygotic twins
- cdz: concordance rate for dizygotic twins
For a pure genetic condition, H is close to 1

17
Q

For different relationships, what is the proportion of alleles family members have in common?

A
  • Monozygotic twins = 1
  • First degree (mom & dad) = 1/2
  • Second degree (aunts & uncles) = 1/4
  • Third degree relatives (cousins) = 1/8
18
Q

What is the recurrence risk for multifactorial conditions for first degree relatives?

A

The square root of the prevalance of the condition on the general population

19
Q

Which population has a higher empiric risk for NTD?

A

Britian

20
Q

Anencephaly

A

Failure of the brain to develop normally. Fatal.

21
Q

Spina bifida

A

Failure of the spine to develop normally

22
Q

Encephalocele

A

Sac-like protusion from base of skull. Frequent mental retardation & neurological defects.

23
Q

Genetics of NTD

A

Mutations in MTHFR 5,10 (methylenetetrahydrofolate reductase) cause instability of the enzyme. This hinders the recycling of tetrahydrofolate and interferes with the methylation of homocysteine to methionine.

24
Q

Mekel-Gruber Syndrome

A

Autosomal recessive condition that can cause polydactyly, encephalocele, polycystic kidneys, and seizures.

25
Q

Multifactorial genetics of diabetes

A

Mutation in PTPN1 (protein tyrosine phosphatase N1) (found in 35% of population) on chromosome 20. The gene product represses the insulin response. Excessive amounts of the protein would decrease inability to responde to insulin and thus people tend to develop diabetes.

26
Q

Chron’s disease

A

Multifactoral inheritance. 20% of cases are causes by mutation on IBD1 (Nod2, Card15) located on chromosome 15. THe gene is responsible for non-specific immune response. Carriers of 1 mutation have 2-3% chance of developing mild Chrons. Carriers of 2 mutations have 20-40% risk of developing severe Chrons.

27
Q

MTHFR

A

Gene involved in development of NTD. Mutations in NTHFR 5,10 (methylenetetrahydrofolate reductase) cause instability of the enzyme. This hinders the recycling of tetrahydrofolate and interferes with the methylation of homocysteine to methionine.

28
Q

PTPN1

A

Gene involved in increased risk of diabetes. Mutation in PTPN1 (protein tyrosine phosphatase N1) (found in 35% of population) on chromosome 20. The gene product represses the insulin response. Excessive amounts of the protein would decrease inability to responde to insulin and thus people tend to develop diabetes.

29
Q

IBD1

A

Gene involved in Chron’s Disease. 20% of Chron’s cases are causes by mutation on IBD1 (Nod2, Card15) located on chromosome 15. THe gene is responsible for non-specific immune response. Carriers of 1 mutation have 2-3% chance of developing mild Chrons. Carriers of 2 mutations have 20-40% risk of developing severe Chrons.

30
Q

Which ethnicity has the highest incidence of CL/P? The lowest?

A

Highest is Asian populations. Lowest is African Americans.

31
Q

What teratogens can cause CL/P?

A

Dilantin, alcohol, valproic acid, anticonvulsants.

32
Q

TGFA, TGFB3, IRF6, MSX1

A

Genes involved in the etiology of non-syndromic oral clefts. The more at risk genes present in the family, the more severe the clefting is.

33
Q

What gense contribute to nonsyndromic oral clefts?

A

TGFA, TGFB3, IRF6, MSX1

34
Q

Van der Woude Syndrome

A

LOWER LIP PITS, hypodontia, cleft lip w/ or w/o palate

  • Autosomal dominant inheritance.
  • Linkage to chromosomes 1 & 17
35
Q

What inheritance pattern does Van der Woude Syndrome follow?

A

Autosomal dominant

MHG (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions