Brainscape's Knowledge GenomeTM

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


See full index

POM (Principles of Medicine) > Genetic disorders > Flashcards

Genetic disorders Flashcards

1
Q

What are the main points for using a genetic pedigree?

A

Provides a clear simple summary of information
Able to spot patterns easily
Explain pattern to patient
Calculate the risk of passing on disease or being a carrier
Allows informed choice

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

How are generations denoted on genetic pedigree?

A

Using roman numerals

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

How are offspring birth ordered traditionally on genetic pedigrees?

A

Left tor right, individuals denote by Arabic numerals.

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

Conventionally, which side is paternal lineage and maternal lineage denoted on a genetic pedigree?

A

Paternal - right

Maternal - left

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

In relation to the proband which % of DNA is shared between grandparents?

A

25%

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

In relation to the proband, which % of DNA is shared between parents?

A

50%

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

In relation to the proband, which % of DNA is shared between siblings?

A

50%

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

In relation to the proband, which % of DNA is shared between Aunts & uncles?

A

25%

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

In relation to the proband, which % of DNA is shared between 1st degree cousins?

A

12.5%

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

What is classified as consanguineous mating?

A

Mating occurs if 2nd cousins or closer (3.13% shared DNA)

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

What pattern is provided by autosomal dominant conditions on a genetic pedigree?

A

Vertical transmission
The tendency for not all offspring expressing the conditions
Both genders are affected
Minimum of one parent required.

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

Why are some familial disorders not expressed within the pedigree?

A

Have an age of onset, developing with age due to an accumulation of sporadic mutations
Decreased patients may not develop the disease, thus not expressed within the pedigree

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

Which trinucleotide repeat causes Huntington’s?

A

CAG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What inheritance pattern is demonstrated by Huntington’s?

A

Monogenic autosomal dominant disorder

Unstable mutation confers for a variable number of repeats

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

How many CAG repeats cause full penetrance?

A

40+

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

Why is the Huntingtin gene unstable?

A

Instability increases over successive generations. CAG is a codon for gutamine, series of repeats results in the production of glutamine chain -Polyglutamine tract/Poly-Q tract
Accumulation of HTT within neurones results in neuronal death
Age of onset decreases with severity and number of repeats

17
Q

What type of gene is MEN1?

A

Tumor suppressor
Affected individuals have one mutation in one allele, over a period of time, second version is mutated, thus there is no active version

18
Q

The development of a second mutation within the MEN1 gene causes what?

A

Leads to the development of benign adenomas

19
Q

How is mitochondrial inheritance conferred?

A

The mutated gene is present in the mitochondrial DNA of the ovum; subsequent.y mtDNA is exclusively inherited from maternal lineages

20
Q

Which lineage has a strong inheritance pattern of mitochondrial DNA?

A

Maternal lineage

21
Q

What type of transmission pattern is evident for mitochondrial DNA inheritance?

A

Vertical transmission

Affects all generations,both genders are affected since the mutated gene is inherited from the mother

22
Q

What are the complicating factors of mitochondrial inheritance in terms of genomes and mt number?

A

Have multiple copies of genome ,therefore a proportion express normal genotype and mutant genotype
Offspring inherit varying numbers of mutated mitochondria this can change with time

23
Q

What is the pattern of inherited mitochondrial disease and age? Explain

A

Diseases develop with age due to accumulation of mutated mitochondria

24
Q

How do mitochondria replicate?

A

Binary fission

25
Q

What is the definition of genetic risk?

A

Risk is the calculation of the predicted chance of having the disease or being a carrier
Risk can only be calculated based upon the known phenotype to subject
Multiplication of risks to calculate overall risk of inheriting genetic disorder

26
Q

What are risk modifiers in terms of phenotypic advantage?

A

The lineages of the disease prevalence (maternal or paternal); X-linked and mitochondrial inheritance patterns
Ethnic background: Diseases have different prevalence in different populations
Example: CF, Sickle cell, Tay-Sachs
Whereby the heterozygous express a phenotypic advantage within the environment, the allelic frequency would increase within areas of relatively higher selection pressure
Founder effect

27
Q

What is the founder effect?

A

Due to a genetic bottleneck, also produced sub-populations with increased prevalence

28
Q

Which inheritance pattern is demonstrated by hereditary hemochromatosis?

A

Autosomal recessive disorder

29
Q

Which protein is the hereditary hemochromatosis allele affecting?

A

Homeostatic iron regulatory protein (HFE)

30
Q

What effect happens due to dysfunctional HFE protein?

A

Excess iron absorption

31
Q

Where is the HFE protein located?

A

Cell surface membrane of hepatocytes

32
Q

Which receptor is the HFE protein associated with?

A

Transferrin receptor i

33
Q

Which plasma protein is bound to transferrin receptor 1?

A

Transferrin

34
Q

How does the HFE protein regulate iron levels?

A

Iron enters hepatocytes, HFE protein regulates iron absorption by preventing transferring from binding to transferrin 1
Regulates the production of hepcidin, Hepcidin determiens level of iron absorbed from the diet and released from storage sites within the body
HFE protein not bound to transferring receptor i ,binds to hepcidin
Formation of complex triggers production of hepcidin - inactivated when bound to TF1

35
Q

How does the HFE gene cause hereditary hemochromatosis?

A

Mutation results in excess iron absorption
Humans cannot excrete excess iron, thus accumulates in tissues
HFE dysfunction results increased absorption of transferrin

36
Q

What is the prevalence of hereditary hemochromatosis?

A

1 in 200 homozygous , 0.5%
10% of these have clinically relevant iron accumulation
0.05% have chronic tiredness fatigue - 7% main symtpom in primary care patients]Therefore 1 in 140 have hH in tiredness group

POM (Principles of Medicine) (34 decks)

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