I am the volunteer administrator of the Alexander Surname DNA Project, in which there are about 210 Alexander men who have tested and compared their DNA.
There IS a lab IN Houston that performs the test, but the location is inconsequential to their business because all correspondence is USPS or internet or phone.
Regarding how you can find if any of your Alexander relatives have taken the test, probably the best approach is for me to email you a file of all our lineages that you can search for your Alexander ancestors.For example, you mention Silas Grandison Alexander who married Nancy Thompson; I believe we have tested 2 descendants of his uncle, Daniel Alexander b. 9 Jul 1767 either MD or NC; d 1829, TN; m. Rachel Mauphet 16 Apr 1794, Cabarrus Co., NC; d. Aft 1822, Smith Co., TN ?.
You and anyone else are welcome to email me at email@example.com.
I hope this helps.
Roger M. Alexander Alexander Ancestry DNA Project Volunteer Coordinator Cincinnati OH H. 513-860-1211 C. 513-702-5373
Alexander Ancestry DNA Project – An all-volunteer effort http://alexanderdna.org/http://alexanderdna.org/ “Helping Alexanders learn Alexander ancestors and cousins”
Order tests at https://www.familytreedna.com/group-join.aspx?Group=Alexander
Contact Roger Alexander – Volunteer Project Coordinator firstname.lastname@example.org