@Kent answer was good, but it seems there's a problem with synIDattr
when one doesn't pass the mode
argument, it fails to return the attribute in GUI mode (gvim). I've learned this from vim-arline plugin sources.
I've solved my problem with:
hi link SyntasticErrorLine SignColumn
exec 'hi SyntasticErrorSign guifg=red ctermfg=red' .
\' guibg=' . synIDattr(synIDtrans(hlID('SignColumn')), 'bg', 'gui') .
\' ctermbg=' . synIDattr(synIDtrans(hlID('SignColumn')), 'bg', 'cterm')