Question on *Anticipation* (Genetics)

[futuredoctor10]

Hey All,

I believe that most of the trinucleotide repeat disorders occur as a result of maternal expansion except Huntington's, which involves expansion by paternal transmission. There is another thread discussing this point.

A question in UW has an explanation that states "Trinucleotide expansion occurs during paternal transmission, causing a genetic phenomenon called anticipation"

Just to make sure, anticipation applies also to expansion during maternal transmission right?
I think the explanation is worded above since the question is about Huntington's, but I want to make sure anticipation applies for any of the trinucleotide repeat disorders with increasing severity of the disease in subsequent generations.

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[Morsetlis]

Anticipation is an increase in severity and decrease in age of onset in successive generations, most likely due to increased size of triple repeats. This could occur during gametogenesis with the meiotic drive: germ cells or meiotic intermediates with expanded repeats have a selective advantage (of not becoming a polar body, for example).

In the case of HD and DM, germ cells possessing expanded
repeats display a selective advantage:
– Higher rate of proliferation
– Altered expression of cell cycle regulators

Common diseases:
Paternal anticipation: Huntington's, Friedrich Ataxia
Maternal anticipation: Myotonic Dystrophy (DM), Fragile X Syndrome (but female affected can mask via lyonization)

 

[futuredoctor10]

Thank you! Great explanation!