What might happen if an alu element was inserted into the exon of
agene?

It is a kind of "Jumping Gene", which is classified as the SINEs (short interspersed elements), a sort of non-autonomous retrotransposon. As they are highly repetitive sequence of the genes.

It was long considered as the junk sequence but now after doing much of the research on it we have came to know that it has a high significance in the genome of the primates and the evolution in the species.

Explanation:

By the process of transposition the sequence of the "transposable element (TE)", is inserted into the introns of the primates genome.

Consequences of insertion:

After doing research we came to the conclusion that the insertion of these sequences in the DNA genome resulted in evolution of the primates. As the  process resulted in the complexity of human neuronal circuitry, along with which it also caused the "higher-order" cognition(rational Thought in the primates).

But, if it is placed on the wrong position it can cause some things more then  just a disorder inside any being's genome.

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