Instead of using loads of seperate variable, use arrays:

my ( @list_total_perl, @perl );

@perl = list_from_wherever();

$list_total_perl[ $_ ] += $perl[ $_ ] for 0 .. $#perl;
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Or if you insist on indexing things with letters, use hashes.

my ( %list_total_perl, %perl );

@perl{ 'a' .. 'e' } = list_from_wherever();

$list_total_perl{ $_ } += $list{ $_ } for 'a' .. 'e';
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