Question

Which of the following can explain anticipation?

(a) Due to slippage of the trinucleotide repeats we will see gradually all the repeat number increases as does the defective phenotype

(b) The child always expresses the phenotype more severely than unaffected parent

(c) The number of repeat beyond a particular threshold leads to improper replication

(d) It is inherited like linkage

This question was posed to me in class test.

My question is from Dynamic Mutation and Anticipation in section Nuclear Export & Post Mendelian Genetics of Cytogenetics

Answer 1

Right choice is (c) The number of repeat beyond a particular threshold leads to improper replication

To explain I would say: In case of anticipation there is a normal range of a number of repeats which can be faithfully replicated. If the number of repeats is beyond a threshold then the faithful replication is lost and massive increase in number is seen in the next generation and yet more in the next.