Gene duplication overview

[file:///home/melvin/Modules/Literature/Hurles2004.pdf]

Mechanisms

\subsection{Retrotransposition} integration of reverse transcribed mature RNAs at random sites in a genome

\subsection{Tandem duplication} One of the possible outcomes of unequal crossing, results from homologous recombination between paralogous sequences. Other outcomes are deletion or inversion of the intervening sequences.

Recent segmental duplication in primates due to rapid proliferation of Alu elements about 40 MYA.

Segmental duplications can also arise from non-homologous mechanisms

\subsection{Genome duplication}

What happens to a recently duplicated gene?

First in order to be observed, it must become fixed in the population and preserved over time.

Approximately above 1/100 genes is duplication and fixed every 1 million years.

\subsection{Nonfunctionalization} Becomes a pseudogene due to degenerative mutations.

\subsection{Neofunctionalization} Gain a new function

\subsection{Subfunctionalization} Original functions of the single-copy gene may be partitioned between the duplicates.

\subsection{Same function} Duplication of gene leads to elevated expression. Histone and rDNA genes are commonly found in arrays of duplicates as this facilitates homogenization by both gene conversion and repeated unequal crossing over.

\subsection{Others} Formation of a novel function due to interaction between the two diverged duplicates. PPI often occur between diverged gene duplicates.

Gene conversion is the non-reciprocal transfer to sequence from one paralogue to the other. Leads to situation where duplicates within a species are highly similar, yet continue to diverge between species. Can also be deleterious, when one of the genes is a pseudogene.