Quiz 2 Flashcards

1
Q

Fragile X has what kind of disorder?

A

CGG in 5’ UTR X-linked

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

Huntington disease is what kind of disorder?

A

AD. CAG (poly glutamine disorder)-coding disorder

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

Freidreich Ataxia has what kind of disorder?

A

GAA in intron; only AR disorder due to trinucleotide repeat expansion

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

Myotonic dystrophy is what kind of disorder?

A

Noncoding in 3’ UTR; means usually parents have it but has not been expressed yet, when doing prenatal testing

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

How is Achondroplasia inherited?

A

AD. Most mutations are the same missense change

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

What perecentage of Achondroplasia is de novo? Whose allele (paternal or maternal) does it arise on and how frequently?

A

90%.

Arises on paternal allele ALWAYS. NOT on maternal allele

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

How would you do diagnosis for Achondroplasia?

A

PCR followed by restriction enzyme digestion

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

For an X-linked disorder how many PCR bands should a male have? Female?

A

Only one band for males; they only have one X. Two bands for females

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

What is penetrance?

A

ON/OFF individually. Infected grandparent, non-affected parent, affect child. Parent would an expression of non-penetrance

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

What is variable expressivity?

A

Dimmer switch - mild to severe

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

Anticipation?

A

Decrease of age of onset (younger disease) or increase in severity in generation from generation

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

Imprinting?

A

Some parts of the genome are not having expression for both mom and dad’s alleles. Either mom’s allele is expressed or dad’s allele is expressed

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

Uniparental disomy? What kind of error is it (M1 or M2)

A

Both chromosomes come from one parent. Error of M2

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

What is known about mitochondrial DNA?

A

Inherited almost exclusively from the mother. High mutation rate. Encodes of all respiratory chain complex EXCEPT for complex 2

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

Why is mutation rate higher in mDNA?

A

No proofreading. No protective histones. At site of oxidative radical formation

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

What is the term for a woman who has wild type and mutant mDNA?

A

Heteroplasmy

17
Q

What does parent of origin mean?

A

Parent of origin= imprinting.

18
Q

Which type of OI is more severe III or IV?

A

III is more severe. II is lethal. I is mild

19
Q

What is the overall incidence of OI?

20
Q

Mutations at which end (carboxy or amino) of Type I collagen are associated with worse phenotype? Where does the helical formation begin?

A

The carboxy terminal, b/c that’s where formation begins (three strands: two alpha1 and one alpha2)

21
Q

All four types of OI can have DI, but type I only happens with a certain type of mutation? What is the type of mutation

A

Missense mutation

22
Q

What is the most probable amino acid affected in COL1A1 mutation? Why?

A

Glycine, every third aa is Glycine. It is the only aa small enough to fit in a pocket

23
Q

Why is Cysteine mutation of COL1A1 tolerated as a mild form but not Aspartate (lethal)?

A

Cysteine is just like Glycine in terms of being non-polar and neutral. Aspartate is polar and acidic, so it is lethal

24
Q

What are the two main mechanisms of OI?

A

Haploinsufficiency and Dominant negative

25
Q

Do you have DI with haplosufficienty in OI? DI with Dominant negative OI?

A

No. Yes. Dominant negative has DI expression.

Bottom line is, not enough collagen is not DI. Mutant type of collagen then there is DI

26
Q

OI has 80% of what kind of mutation? 20% of what typeof mutation?

A

80% substitutions for glycine in either type 1 collagen chain.
20% cause abnormalities of splicing

27
Q

Which type of OI is lethal and can be ruled out?