I dont know about the "gothic" aspects of vampires (IE, living only at night, drinking blood, ect), however, the immortality part I believe is a
possibility.
Telomeres are a genetic "defect" in the human DNA, that essentially serves to act as a time bomb... they tell your DNA when to stop dividing and
reproducing, and once that happens, you live on what cells you have, which die off eventually never to be replaced, until you die of old age.
freedom.orlingrabbe.com...
I can believe that some individuals throughout history have been born with no telomeres, or some genetic mutation deactivates thier telomeres... if
this were to happen, thier DNA would go on reproducing almost indeffinitely, which means at least a far extended lifespan, if not an endless one.