Classification of mutations by their effects in function

Question 1

Mutations may usefully be classified by their
effects on protein function into _____, ______, and _____.

Answer 1

loss - of - function; gain - of - function; dominant - negative mutations

Question 2

_____ mutations cause a reduction in the activity or amount of the encoded protein and include most mutations.

Answer 2

Loss - of - function

Question 3

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.

Answer 3

recessive inheritance

Question 4

If the 50% level of activity is insufficient, then the loss-of-function mutation is said to result in _____ and dominant inheritance results.

Answer 4

haploinsufficiency

Question 5

If the 50% level of activity is insufficient, then the loss-of-function mutation is said to result in haploinsufficiency and _____ results.

Answer 5

dominant inheritance

Question 6

Mutations affecting the _____ gene, results in haploinsufficiency causing Léri – Weill dyschondrosteosis.

Answer 6

SHOX

Question 7

Mutations affecting the SHOX gene, results in haploinsufficiency causing ______.

Answer 7

Léri – Weill dyschondrosteosis

Question 8

______ 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.

Answer 8

Gain - of - function

Question 9

RET mutations are a gain-of-function mutation that results in greater level of gene activity. This causes what disease?

Answer 9

Multiple endocrine neoplasia type 2

Question 10

Example of a gain-of-function mutation that results in the acquisition of a new function.

Answer 10

BCR-ABL chimeric gene after chromosomal translocation

Question 11

_____ 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.

Answer 11

Dominant - negative mutations

Question 12

Dominant - negative mutations include some mutations in _____, the gene that encodes fibrillin and is associated with Marfan syndrome.

Answer 12

FBN1

Question 13

Dominant - negative mutations include some mutations in FBN1, the gene that encodes ____ and is associated with Marfan syndrome.

Answer 13

fibrillin

Question 14

Dominant - negative mutations include some mutations in FBN1, the gene that encodes fibrillin and is associated with _____.

Answer 14

Marfan syndrome