Existing Wording: Because DNA, RNA and even amino acid sequences can be exceptionally long - and are typically mostly the same for a given type of organism or protein - reporting is typically done on the basis of variations between the tested specimen and a reference specimen rather than as a complete enumeration of the whole sequence.

Proposed Wording: Because DNA, RNA and even amino acid sequences can be exceptionally long - and are typically mostly the same for a given type of organism or protein - reporting is typically done on the basis of variations between the sequence in the tested specimen against a and a reference sequence rather than as a complete enumeration of the whole sequence.

Comment:

The reference is always a sequence. Not a specimen.

Summary:

Fix language from specimen -> sequence