I know this post is kinda old but I recently found out that were are directly related to a set of Jefferson from Abbeville, South Carolina. I haven't found the proof yet but majority of the slaves found in Abbeville in my family listed there parents orgins to be VA. Im not sure what the significance of this is. I believe that there definately was a trading rount somewhere between VA and Abbeville, South Carolina.
Also I have completed two dna test on my father's side which is Jefferson by blood. The test results I did with DNAtribes.com say that our dna is primarily affilated with the Levantine area. Levantine encludes Egypt. Also our highest resolution population matches are North West Spain(perhaps Celtic) and then Egypt.
On another test I took with 23andme.com designates my grandfathers paternal dna as E2B1 and his maternal haplogroup as L3f1b3. I wonder could there be a connection between the Jeffersons you mention and mine.