Classification of mutations by their effects in function Flashcards
Mutations may usefully be classified by their
effects on protein function into _____, ______, and _____.
loss - of - function; gain - of - function; dominant - negative mutations
_____ mutations cause a reduction in the activity or amount of the encoded protein and include most mutations.
Loss - of - function
Loss - of - function mutations can underlie ______, e.g. if the resulting 50% of protein activity in a carrier of such a mutation is sufficient for normal cellular function.
recessive inheritance
If the 50% level of activity is insufficient, then the loss-of-function mutation is said to result in _____ and dominant inheritance results.
haploinsufficiency
If the 50% level of activity is insufficient, then the loss-of-function mutation is said to result in haploinsufficiency and _____ results.
dominant inheritance
Mutations affecting the _____ gene, results in haploinsufficiency causing Léri – Weill dyschondrosteosis.
SHOX
Mutations affecting the SHOX gene, results in haploinsufficiency causing ______.
Léri – Weill dyschondrosteosis
______ mutations, w/c are less common than loss of function mutation, result in a greater level of activity, a greater amount of protein or, more rarely, acquisition of a new function.
Gain - of - function
RET mutations are a gain-of-function mutation that results in greater level of gene activity. This causes what disease?
Multiple endocrine neoplasia type 2
Example of a gain-of-function mutation that results in the acquisition of a new function.
BCR-ABL chimeric gene after chromosomal translocation
_____ are those that generally impair the function of the protein encoded by the mutant gene copy and also, as a result of protein – protein interactions reduce the function of the protein encoded by the normal copy of the gene.
Dominant - negative mutations
Dominant - negative mutations include some mutations in _____, the gene that encodes fibrillin and is associated with Marfan syndrome.
FBN1
Dominant - negative mutations include some mutations in FBN1, the gene that encodes ____ and is associated with Marfan syndrome.
fibrillin
Dominant - negative mutations include some mutations in FBN1, the gene that encodes fibrillin and is associated with _____.
Marfan syndrome