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Fundamentals of neuroscience > Ion channel disorders (diseases of NS) > Flashcards

Ion channel disorders (diseases of NS) Flashcards

1
Q

What is a chennelopathy?

A

Disease or pathology associated with ion channel dysfunction

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2
Q

What can channel mutations effect?

A

Functional expression, permeation or gating

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3
Q

What are 3 types of channelophathy?

A
  • Autoimmune
  • Environmental toxicology
  • Abberatn expression
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4
Q

What are some autoimmune channelopathies?

A
  • Myasthenia gravis
  • Lamert Eaton myasthenia syndrome
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5
Q

What are some evironmental toxicology channelopathies?

A

Heavy metal poisoning

e.g. Cd2+, Hg+, Pb+

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6
Q

What are some abberant expression channelopathies?

A
  • Regulation (accessory subunits)
  • Trafficking (Chaperones)
  • Localisation (e.g. Ankyrins)
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7
Q

What are the 3 types of point mutations?

A
  • Silent mutation
  • Conserved point mutation
  • What is a missence point mutation

(Only one base changes)

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8
Q

What is a silent mutation?

A

One base in a codon changes but does not affect the amino acid produced

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9
Q

What is a conserved point mutation (T1S)?

A

Occurs in a highly conserved region of DNA & typically results in a conservative amino acid substitution

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10
Q

What is a missence point mutation?

A

A type of point mutation in which a single nucleotide change resultd in a codon that codes for a different amino acid

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11
Q

What is are the types of frameshift mutations?

A
  • Insertion
  • Deletion
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12
Q

What is an insertion and what does is cause?

A

When one or more amino acids are inserted into the DNA sequence (shifts the DNA right by one or however many places)

This can lead to nonsence

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13
Q

What is a deletion mutation?

A

When one or more amino acids are deleted in the DNA sequence (DNA shifts left by however many were deleted)

This leads to truncation

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14
Q

What is malfunctions (in relation to ion channel mutations)?

A

Loss of function OR gain of function

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15
Q

How do mutations alter ion channel function?

A

A - mutations alter permeation pathways = mutant channel opens but permeation is altered

B - Mutations change channel activation

C - Mutations change channel inactivation process

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16
Q

Give a few examples of channelopathies:

A
  • Asthma
  • Epilepsy
  • Dementia
  • Cancer
  • Diabetes
17
Q

Name some common NS channelopathies:

A
  • Epilepsy & migraine
  • Neuromuscular disorders
  • Cerebellar and execessive startle
18
Q

Give some examples of neuromuscular diorders

A
  • Myasthenia (nicotinic)
  • Myatonia (Na+, Cl-)
  • Periodic paralysis (Na+, K+, Cl-)
  • Pain erythma (Na+)
19
Q

Which channels can cause epilepsy and migraines?

A
  • Epilepsy = Na+, K+, Ca2+, GABAA, Nicotinic
  • Migraine = Na+, Ca2+
20
Q

Which channels can cause cerebellar ataxia & excessive startle?

A
  • Ataxia = K+, Ca2+
  • Hyperplexia = Glycine
21
Q

What are some cardia channelopathies?

A
  • Long QT syndrome
  • Bugada syndrome
  • Sudden infant death syndrome (SIDS)
22
Q

What are the ion channels in long QT syndrome?

A
  • Numerous forms
  • 6 ion channels (NaV, KV, CaV)
  • 6 ion channel modulatory proteins
23
Q

What are the ion channels in Brugada syndrome?

A
  • 2 ion channels (NaV, CaV)
  • 4 modulatory proteins
24
Q

What causes long QT syndrome?

A
  • Prologation of ECG QT interval
  • Slowed repolarisation phase of AP
25
Q

What precipitates long QT syndrome?

A

Preceipitated by exercise, arousal, loud noises

26
Q

When does long QT syndrome manifest & what is its incidence?

A

In children and teenagers

Prevalance = 1:5,000

27
Q

What are the symptoms of long QT?

A
  • Life threatening cardiac arrhythmias, syncope (fainting), seizures, death
  • Leads to ventricular fibrillation
28
Q

What is the most commone type of long QT?

A

LQT1 - most common, least severe

35% prevalence among LQTS patients

29
Q

What mutation causes long QTS?

A

Many mutations in KCNQ1 gene = KV7.1 (KVLQT1) slow delayed rectifier K+ current

V254M/L most common missence mutation (valine to methionine/leucine at pos. 254 in S4-S5 linker)

30
Q

Watch lecture vid on KCNQ1 channel mutation

A

Thank u

31
Q

What does KV7.1 (KVLQT1) cause?

A

(Main channelopathy that underlies LQT1)

  • Activation of this causes major repolarising current of phase 3 of the cardiac AP
  • Mutation causes loss of function = slow repolarisation (explains effect)
32
Q

What is dominant negative effect?

A

Mutant K+ channel subunits (mt) form tetramers with wild type (wt) subunits: 4 subunits make a K+ channel (heteromization)

  • Expression in the heterozygote: 50% wt and 50% mt
  • Random association the the cell (so any cell could be mutated or not)
33
Q

Finish from slide 15

A

Fundamentals of neuroscience (38 decks)

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