Diseases of Nervous System

Question 1

What are the three types of developmental and genetic disease

Answer 1

Down syndrome
Tay sachs disease
Spina Bifida

Question 2

Describe three pattern of Down syndrome

Answer 2

1.Trisomy 21
-characterised by failure of chromosome 21 to separate during meiosis
-the risk to have this pattern increase with maternal age
2.Robertsonian translocation
-characterised by the translocation of chromosome 21 at other neuron.
-it happens after fertilization
-usually the carrier does not show any characteristic of DS
3.Mosaicism
-has milder features
-occurs postzygotically
-some child will have DS, some are not if one of the parent is the carrier

Question 3

Explain the tay sachs disease and its pathogenesis

Answer 3

-Tay-sachs disease is the rare autosomal recessive.
-It caused by the absence of enzyme to break down the fatty substances called GM2 gangliosides. This lead to the build up to toxic levels in the brain and spinal cord.
-In normal people, **Hexoaminidase A will instructs the making of B-Hexosaminidase A enzyme in lysosome. Then, the enzyme will degrade the fatty substance called GM2 gangliosides.
-However, in TSD people, the Hex-A mutated and disrupt the making of B-Hex A enzyme and its enzyme activity. Therefore, it cause the accumulation of GM2 gangliosides to the toxic level in neuron of the brain and spinal cord.
-Lead to neuron destruction**

Question 4

Explain the clinical features of TSD

Answer 4

1. Neurological symptoms
-loss of motor function -Cause delay in development in infants. For example, in crawling and walking stages.
-loss of loss of mental function and lack of response to the surrounding
2. Physical symptoms
-cherry red spot
-muscle weakness - characterised by hypotonia (decreased muscle tone). It leads to difficulty with movement and coordination
-vision loss and blindness
-hearing loss and blindness
3.Behavioural changes
-exaggerated startle response when baby hears loud noise

Question 5

What are the types of infections in CNS

Answer 5

Meningitis
Encephalitis
Cerebral Abscess

Question 6

What are the common pathogens that affect the meningitis?

Answer 6

-Neonates- E.coli & grp B streptococcus
-Infants & children- Haemophilus influenza
-Young adults- Neisseria meningitis
-Adults- Streptococcus pneumonia & Listeria monocytogenes

Question 7

Two types of degenerative disease

Answer 7

-Alzheimer’s disease
-Parkinson’s disease

Question 8

Pathogenesis of Alzheimer’s disease
(Formation of neurofibrillary tangles)

TAU protein involved

Answer 8

Formation of neurofibrillary tangles
Normal:
1. neuron communicates through the signals from the body to synapse.
2.The signal then passes the neuron skeletal containing microtubules (stabilized by TAU protein)
AD
1.TAU protein bcm defective and detach from the microtubules.
2. This causes the microtubules to become unstable and disintegrate.
3. So, the communication between neuron loss
4.TAU protein form neurofibrillary tangles that causes neuron death

Question 9

Pathogenesis of Alzheimer’s disease
(Formation of amyloid-B plagues)

Answer 9

Normal: (non amyloidogenic)
1. on the neuron surface, there are APP (amyloid precursor protein)
2.APP cleavage by alpha-secretase and gamma-secretase producing harmless soluble peptides
AD; (amyloidogenic)
1.APP cleavage by B-amyloid converting enzyme and gamma-secretase
2. It produce AB-peptides and ths will aggregates
3.Forming Amyloid-B plague
4.It will disrupt the communication between neuron and leads to inflammation