Question

2.a Which of the following is unlikely to be a risk factor for Alzheimer's (choose all that apply)?

1. Age
2. inheriting a mutation that causes a deletion of the APP gene
3. smoking
4. inheriting a hypoactive allele of Presenilin 2 gene
5. inheriting the APOE4 allele
6. inheriting an extra copy of the APP gene

2.b Amyloid beta protein fragments (choose all that apply):

1. Result from proteolytic Cleavage by alpha and beta secretase enzymes
2. Are typically greater than 45 amino acids in length
3. Can be degraded by Neprilysin.
4. Result from proteolytic cleavage by beta and gamma secretase enzymes
5. Can be removed from extracellular regions by astrocytes and microglia

2.c Which of the following is a common feature of Alzheimer’s brain tissue? Choose all that apply.

1. Widened sulci
2. Atrophy of the cerebellum
3. Abnormal enlargement of the hippocampus
4. Narrowed gyri
5. Reduction in the volume of ventricles (containing cerebral spinal fluid)

2.d Which of the following is associated with Moderate Alzheimer's disease? Choose all that apply.

1. short term memory loss
2. language deficits
3. social withdrawal
4. loss of motor skills
5. incontinence

2.e Tay Sachs is typically diagnosed:

1. By determining the organelle localization of HexA in neuronal samples
2. By measuring HexA enzymatic activity in various bodily tissues/fluids
3. Through genetic counseling
4. All of the above.

2.f An individual with ____________ Tay Sachs is likely to develop motor difficulties in their 30’s.

1. Chronic
2. Late-onset
3. Juvenile
4. None of the above

Answer 1

2a. Correct answer is d.

Age is the greatest risk of this disease is the increasing age and that why this disease is seen mainly in patients above 65 and further as the age progresses the risk factor increases. Although early onset alzheimer is seen in patients in their 30 and 40's

Basically, APP gene, Presinilin gene and APOE4 genes are primarily responsible for alzheimer disease. If one inherits this gene that is mutated resulting in deletion of APP gene, further their will be base pairing changes and resulting in change in sequence.

People with smoking has doubled the risk of this disease.

Since mutation in presinilin gene causes this disease, inheriting this hypoactive allele of this gene will make it less likely to cause this disease, since this gene would be nonfunctional or inactive.

APOE is the main cause of this disease and inheriting this gene would increase the risk of this disease. Amyloid plaques (accumulation of fibres in brain) tends to accumulate in brain causing this disease. This plaque consist of harmful beta amyloid proteins.

Addition copy of APP gene increases the risk factor of developing this disease more. Chromosome 21 has APP gene on it. Down syndrome is caused by any abnormalities in cell division that results in extra or partial copy of this chromosome. So, patient with dowm's syndrome is at higher risk of developing this disease.

2b. Correct ans is c,d and e

Amloid beta protein fragments results from cleavage between beta and gamma secretase to give alpha-beta molecule and not between alpha and beta secretase.

They range between 28-43 amino acids.

Neprilsin degrade this fragment which causes abnormal folding and aggregation in neural tissue causing alzheimer disease.

They result from cleavage between beta and gamma secreaase enzyme to yield alpha beta molecule.

These fragments can be removed by microglia and astrocytes as an reaction to inflammatory response in alzeihmer's disease. They acts in a inflammatory signaling pathway. They are the first cells to be acted on the site of injury during inflammation. They play crucial role in phagocytosis.

2c. Correct ans is a,b and d

widened sulci is observed

Atrophy of cerebellum is also seen as age is the major risk factor in this disease.

There is a shrinkage of hippocampus in alzheimer disease.

There is a shrinkage i.e narrowing of gyri seen.

There is a enlargement in volume of ventricles

2d. Correct ans is a,b,c

This is associated with short term memory loss and slowly slowly it progresses along with age.

As the age progresses their is a language impairment observed.

Social withdrawal can also be seen due to language difficulties, anger etc,

Decrease in motor function is seen specially in moderate alzheimer disease but complete loss of motor skills can be seen in severely affected patients.

Incontinence develops later in stage of this disease.

2e. Correct ans is d

Since this is neurodegenerative disease , diagnose is via determination of localization of Hex A in neural samples.

Since this is because of Hexosaminidase A deficiency, diagnosis is via measuring the enzymatic activity in body fluids

This diagnosis is quite complex, it starts with genetic counseling first.

2f. Correct ans is b.

Infantile TSD- patient is of age upto 6 months

Juvenile TSD- patients of age 2-10

late/adult TSD- patients of age 20-30