Channelopathies Flashcards
what is a nonsense mutation?
when a pt mutation results in a stop codon
what is a fram shift mutation
when an extra aa is inserted
dominant negative is
when a protein produced by mutated gene affects normal one
haploinsufficiency=
when both genes needed for function, if one missing other can’t cope
hyperekplexia is a mutation of ___ and is also know as ___
glycine receptor channels, startle/stiff baby disease
hyperekplexia is a ____ _____ disease, and it’s genetic linkage is to a ____ on _____ at chromosome _____
autosomal dominant, point mutation, R271Q, 5q32
R271Q means
mutation at arginine at 271, to glutamine
what gene is R271Q contained within?
GLRA1, glycine receptor alpha 1 subunit
what is the result of the point mutation in hyperekplexia?
a reduced glycinergic inhibition in the spinal cord, leading to exaggerated reflexes, hypertonia (because of spontaneous release of Ach) and exagg. startle response
GEFS=
generalised epilepsy with febrile seizures, results in convulsions+fever+tendency to develop epilepsy
GEFS is a ___ ___ disease, which occurs because of a ___ ___ in _____ of the _____ gene. This occurs in chromosome ______
autosomal dominant, point mutation, C121W, SCN1B, 19q13.1
C121W means
cysteine at 121 to tryptophan
SCN1B gene is
a sodium channel beta 1 subunit gene
what is the channelopathy of GEFS
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
what does channelopathy of GEFS not explain?
why in most cases symptoms resolve even though problem persists
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 ____
pore forming, voltage sensing, kinetics
Bfnc=
recurrent early seizure, spontaneiously recovers after 3 months, increased rick developing epilepsy
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 _______
haploinsufficiency, frameshift, stop codon, 300 amino acid deletion, KCNQ2, 20q13.3
KCNQ2=
mutation of potassium channel of the Q family
