Why would you thish using dna , rna, prteoin to diagnosis entrovirus, rna respitory virus ?

1- Why would you thish using dna , rna, prteoin to diagnosis entrovirus, rna respitory virus ? why would you think using dna, rna, , protein to diagnosis hemochromatosis? why would you think using dna, rna, , protein to diagnosis guillain–barre syndrome ? 2- How would you diagnosis all of these disease by cell extract or gel electrophoresis or blotting? Explain what the sample u need from patient and what molecules you need to perform ? 3- How would you do all of these disease in pcr what material you need to do and measure ?