Channelopathies

Question 1

what is a nonsense mutation?

Answer 1

when a pt mutation results in a stop codon

Question 2

what is a fram shift mutation

Answer 2

when an extra aa is inserted

Question 3

dominant negative is

Answer 3

when a protein produced by mutated gene affects normal one

Question 4

haploinsufficiency=

Answer 4

when both genes needed for function, if one missing other can’t cope

Question 5

hyperekplexia is a mutation of ___ and is also know as ___

Answer 5

glycine receptor channels, startle/stiff baby disease

Question 6

hyperekplexia is a ____ _____ disease, and it’s genetic linkage is to a ____ on _____ at chromosome _____

Answer 6

autosomal dominant, point mutation, R271Q, 5q32

Question 7

R271Q means

Answer 7

mutation at arginine at 271, to glutamine

Question 8

what gene is R271Q contained within?

Answer 8

GLRA1, glycine receptor alpha 1 subunit

Question 9

what is the result of the point mutation in hyperekplexia?

Answer 9

a reduced glycinergic inhibition in the spinal cord, leading to exaggerated reflexes, hypertonia (because of spontaneous release of Ach) and exagg. startle response

Question 10

GEFS=

Answer 10

generalised epilepsy with febrile seizures, results in convulsions+fever+tendency to develop epilepsy

Question 11

GEFS is a ___ ___ disease, which occurs because of a ___ ___ in _____ of the _____ gene. This occurs in chromosome ______

Answer 11

autosomal dominant, point mutation, C121W, SCN1B, 19q13.1

Question 12

C121W means

Answer 12

cysteine at 121 to tryptophan

Question 13

SCN1B gene is

Answer 13

a sodium channel beta 1 subunit gene

Question 14

what is the channelopathy of GEFS

Answer 14

mutation results in a C and a W in the C loop rather than 2Cs, so disulphide bond cant form so no c loop so rate of inactivation of the beta subunit slows

Question 15

what does channelopathy of GEFS not explain?

Answer 15

why in most cases symptoms resolve even though problem persists

Question 16

beta subunits of the voltage gated sodium channel are not ____ ___ or ___ ____, rather they can coassemble with the large self sufficient alpha subunit and alter its ____

Answer 16

pore forming, voltage sensing, kinetics

Question 17

Bfnc=

Answer 17

recurrent early seizure, spontaneiously recovers after 3 months, increased rick developing epilepsy

Question 18

BFNS is a _____ genetic disorder, due to a _____ mutation that results in a ____, which brings about a _________. This mutation occurs at _____ of chromosome ______ and results in a potassium channel that is _______

Answer 18

haploinsufficiency, frameshift, stop codon, 300 amino acid deletion, KCNQ2, 20q13.3

Question 19

KCNQ2=

Answer 19

mutation of potassium channel of the Q family