Molecular typing from cDNA molecules lacks which feature that may require a change in methodology from genomic typing?

Molecular typing from cDNA molecules focuses on the expressed genes, which means that only the coding sequences (exons) and their associated regulatory sequences are analyzed. In contrast, genomic DNA encompasses both coding and non-coding regions, including introns.

When transitioning from genomic typing to cDNA typing, the absence of introns in cDNA is a critical factor. Introns are non-coding sequences spliced out during the process of mRNA maturation; since cDNA is derived from mature mRNA, it contains only the exonic sequences. This fundamental difference can necessitate changes in methodology, as techniques that target intronic regions or rely on the presence of introns for amplification or analysis would not be applicable to cDNA typing.

Understanding this distinction is essential for accurately interpreting results in genetic typing and ensuring the chosen methodologies are compatible with the type of nucleic acids being used.