The puzzle is presented as a sequence of DNA bases. Translating into amino acids and representing using the standard single-letter code gives the following strings, separated by stop codons:

CRPERYISCTAELLINNATLRPHIANA
CNYINEICLNINK
CHEASPEIARNAKANPPAASE
CACLPAYCLINSTATIHN
TRADYMNESTHYRCETLIINN
SCAMIPHINPDEHRYSININ
SAYNEMGGRIECANN
HAISRGITNIYDYLLTRTNRASNYANTSHYNTETAHESTASEE
PSEYPMTPLIDAEKSEIND
SENTAMATHELEIRINN
CENAHAVTAHSEPSPILIKNGE
NFAASLDIKGAINNASDE
NISVILCHLINLAIRKIEN
PGLASDEECRTMIINCN
PESPERTIDYLAYLTRGRINNIASYNENDETIMHINASEETYTPAESIVE
GAESPPARHAGIYNASRIEN
FEILLAMIANCGSTAINMMA
VLAERSIEVECRANIN

Each of these strings consists of the intertwined names of two human genes (standard names can be found at http://www.genenames.org/), and each pair of genes is located on the same human chromosome. Indexing chromosome numbers into the alphabet gives the clue UNDERGOES DNA CHANGE, giving the answer MUTATES.

Here is a full table of the genes used in the puzzle:

Gene 1	Gene 2	Chr	Clue
CRYSTALLIN ALPHA A	PERICENTRIN	21	U
CYCLIN K	NINEIN	14	N
CASEIN KAPPA	HEPARANASE	4	D
CALPASTATIN	CYCLIN H	5	E
TRANSTHYRETIN	DYMECLIN	18	R
SCINDERIN	AMPHIPHYSIN	7	G
SYNEMIN	AGGRECAN	15	O
HISTIDYL-TRNA SYNTHETASE	ARGINYL-TRNA SYNTHETASE	5	E
PEPTIDASE D	SYMPLEKIN	19	S
STATHERIN	ENAMELIN	4	D
CATHEPSIN G	ENAH/VASP-LIKE	14	N
NAD KINASE	FAS LIGAND	1	A
NISCHARIN	VILLIN-LIKE	3	C
PLECTIN	GASDERMIN C	8	H
PEPTIDYL ARGININE DEIMINASE, TYPE IV	SERYL-TRNA SYNTHETASE	1	A
GEPHYRIN	ASPARAGINASE	14	N
FILAMIN C, GAMMA	ELASTIN	7	G
VERSICAN	LAEVERIN	5	E