I require some clarification on copy number aberrations (structural gain and loss in chromosomes). From what I understand, gain/loss per se can be divided into two types.
Consider two alleles, A and B at the same locus on homologous chromosomes.
Allelic Balance: in one type of structural gain/loss, there is no resulting allelic imbalance; examples:
- AB ==> AABB (duplication),
- AB => -- (loss).
Allelic Imbalance: in the other type of structural gain/loss, there is resulting allelic imbalance; examples:
- AB ==> AAB (duplication of A),
- AB => -B (deletion LOH),
- AB ==> BB (copy-neutral LOH).
First, is what I have described above correct?
Second, if it is correct, what is the biology underpinning these copy number aberration types? Are the mechanisms responsible for bringing about allelically-imbalanced CN change distinct from the mechanisms for bringing about allelically-balanced CN change? What are these mechanisms?
NB. I'm confining this to just copy number-related allelic imbalance.