[VOA]

a mutation is less genetic information and results in disease.

Not always.
Sometimes the change in a single nucleotide will still code for the
same amino acid...hence you can (if lucky) have a mutation that
is "silent"...and would go unnoticed, but for sequencing of the
DNA sequence of the gene from other people without the mutation.

[tomzz]

I saw a thing on film recently in which a reporter asked Richard Dawkins if he could name a single case of a mutation which resulted in an increase in information, and the guy was totally stumped; he just sat there with a dumb look on his face for a whole minute or thereabouts.