Diseases For PNT

Question 1

Congenital myasthenic syndromes

Answer 1

Inadequacy in vesicles due to decreased supply or impaired endocytosis that leads to an impaired endosomal recycling mechanism

Especially prominent on repeated stimulation: inadequate number of synaptic vesicles available for release during sustained presynaptic activity

Some of these affect the AChE
Others cause autoimmune attack of AChR

Weakness and fatiguability of skeletal muscles

Question 2

Familial infantile myasthenia

Answer 2

Synaptic vesicles that are smaller in diameter but normal in number - problems in initiating voluntary movement

Question 3

Lambert-Eaton Myasthenic Syndrome

Answer 3

Autoimmune destruction of CaV in presynaptic membrane of motor neurone. So voltage is not enough for vesicle release.
Occasional complication in patients with certain types of cancers
Number of quanta released decreases but not size of MEPPs so doesn’t affect size of quanta.

Question 4

Dopamine beta hydroxylase deficiency

Answer 4

Failure of NA synthesis resulting in severe orthostatic hypotension