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MGM Exam 2 (C) > Diseases > Flashcards

Diseases Flashcards

1
Q

What are the clinical features of Fragile X Syndrome?

A

long face
big ears
hyperextensible joints
moderate/ severe mental retardation in males
learning disabilities/ mild retardation in females

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2
Q

What is the inheritance pattern of Fragile X Syndrome?

A

X linked dominant with Sherman Paradox

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3
Q

What is a key feature of Fragile X Syndrome pedigrees?

A

Males never have affected daughters and the reason for that is unknown.

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4
Q

Premutation females have what number of CGG repeats in Fragile X Syndrome?

A

50-100 CGG repeats

They have a normal phenotype but have a high risk of having affected offspring.
70 CGG = 50% of offspring will have full mutation
> 90 CGG = always pass on full mutation to offspring

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5
Q

What is the genetic basis of Fragile X Syndrome?

A

It is when you have 800-1000 CGG repeats. This is a huge expansion that prevents transcription due to CpG hypermethylation in 5’ UTR. It expresses no FMR-1 mRNA. There is a loss of function.

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6
Q

What is the Sherman Paradox?

A

It is when there is an increasing risk of full expansion (affected children) depending on the size of their allele.

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7
Q

What is the inheritance pattern of Myotonic Dystrophy?

A

Autosomal dominant with anticipation

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8
Q

What is anticipation?

A

Anticipation is when there are more severe symptoms and earlier onset in successive generations. There is a successive generational expansion of CTG triplet.

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9
Q

What are the clinical features of Myotonic Dystrophy?

A

Normal intelligence
Mild Cases: cataracts, prefrontal baldness, no mytotonia
Adult Onset: muscular dystrophy and cardiac arrhythmia
Severe Cases: congenital onset and rapid progression of muscle degradation

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10
Q

What is the genetic basis of myotonic dystrophy?

A

There is a CTG expansion in the 3’ UTR of the DM-1 gene.

400: adult onset
>1000: congenital

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11
Q

T/F: DM-1 protein is not made in normal amounts in the affected patients of Myotonic Dystrophy.

A

False. DM-1 is made in normal amounts but the defect is caused by gain of function in DM-1 mRNA (i.e. toxicity).

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12
Q

What is locus heterogeneity?

A

Is is when mutations on different genes cause the same disease. For example, CCTG mutations on a second locus ZnF9 causes DM-2, which has the same phenotype as DM1 which is caused by mutations on DMPK gene.

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13
Q

What is the inheritance pattern of Huntington’s Disease?

A

Autosomal Dominant with anticipation

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14
Q

What are the clinical symptoms of Huntington’s Disease?

A

Progressive chorea (jerky movements)
Rigidity
Dementia
Death 10-15 years after onset

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15
Q

Age of onset correlate with ______ in Huntington’s Disease.

A

the number of CAG triplet repeats in the protein coding region of the gene.

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16
Q

Why is there variability in the age of onset in HD?

A

It is caused by anticipation! A small increase in the number of CAG repeates causes a decrease in the age of onset

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17
Q

T/F: HD is caused by a gain of function toxic protein that has larger poly-glutamine tract.

A

True.

18
Q

What is another name for Kennedy disease?

A

Adult onset spinal bulbar muscular atrophy

19
Q

T/F: The androgen receptor gene is X-linked.

A

True.

20
Q

What is the genetic basis for Kennedy disease?

A

It is caused by expansion of the CAG triplet in the coding region of AR gene causes GAIN OF FUNCTION in the androgen receptor.

21
Q

What causes complete testicular feminization?

A

It is caused by androgen receptor LOSS OF FUNCTION causing XY females.

22
Q

What is the inheritance pattern of multifactorial diseases?

A

Autosomal dominant (predisposition)

23
Q

What is thrombophilia?

A

It is the propensity to form blood clots within blood vessels: deep vein thrombosis

24
Q

What is the primary cause of pulmonary embolisms?

A

DVTs

25
Q

What causes Factor V Leiden Disease?

A

G to A mutation causes ARG –> GLN substitution in proteins.
Protein C does not inactivate Factors 5,8

26
Q

What causes Long QT syndrome?

A

It is caused by mutations in potassium channels which cause the slow repolarization of membrane causing a long QT interval

27
Q

What does Long QT mutations give you predisposition to?

A

Arrythmia and sudden death

28
Q

What is the treatment for Long QT?

A

pacemakers and drug therapy

29
Q

Why don’t 100 percent of twins both have hypertrophic cardiomyopathy?

A

Genetics is just a predisposition, not a guarantee for the disease.

30
Q

What is hypertrophic cardiomyopathy?

A

It is the thickening of the walls of the heart.

31
Q

What are two of the most common genes that predispose you to HCM?

A

MYBPC3 and MYH7

32
Q

What is the most common cause of sudden death in young adults?

A

HCM (hypertrophic cardiomyopathy)

33
Q

What are some treatments that are available for HCM patients?

A

genotyping array
implanted defibrillators
test family members/ young athletes

34
Q

T/F: Mutations in cardiac contractile protein genes are known to increase risk for HCM.

A

True.

35
Q

What is Alzheimer’s disease?

A

It is a central nervous system neurodegenerative disorder with a progressive loss of cognitive function and dementia.

36
Q

What causes death in patients with Alzheimer’s disease?

A

Death from malnutrition, infection and heart disease

37
Q

What percentage of people have early onset autosomal dominant Alzheimer’s Disease?

A

5%

38
Q

What genotype is high risk for late onset Alzheimer’s?

A

E4E4

39
Q

Mutations in which three genes can predispose you to early onset Alzheimer’s?

A

APP
presenilin1
presenilin2

40
Q

Common variants in _______ predispose you to classic Alzheimer’s disease.

A

apolipoprotein E

41
Q

Accumulation of which aberrantly processed polypeptide causes Alzheimer’s?

A

beta amyloid polypeptide

MGM Exam 2 (C) (11 decks)

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