The CCR5 gene encodes a chemokine receptor (a long name for a protein that sits in the walls of our cells).When the body has been invaded by a pathogen such as a cold virus, CCR5 plays an important role in fighting that virus.Smart viruses such as HIV-1, however, hijack the CCR5 protein and use it to sneak into CD4+ T cells & macrophages.
In some populations the CCR5 gene has experienced a mutation that deleted 32 basepairs in the gene sequence.The mutation prevents the expression of the protein on the cell surface.As a result, people with this mutation show some degree of protection from certain viruses.In fact, homozygosity of the CCR5-D32 allele (meaning BOTH copies of the gene are mutated) leads to “nearly complete resistance to HIV-1 infection.”People with only 1 copy are as much as 70% resistant! Surprisingly, homozygotes do not show any other problems as a result of the mutation.
My first foray into genetic genealogy took place in 2003 when I ordered the mtDNAPlus (which sequences both HVR1 and HVR2) from Family Tree DNA.
Like so many other genealogists, I had been unable to trace my maternal line as far as I would have hoped.My most distant ancestor, Sarah L. Bodden, was born in 1846 in the Cayman Islands and had died in 1914 in Honduras.No one knew anything about Sarahâ€™s parents or her life, and given the location and the difficulty of research I felt that this line had little prospect of development.It was a perfect opportunity to employ genetics.
Inside (almost) every one of my 50 trillion cells (thatâ€™s 50,000,000,000,000!!!) there is a tiny circle of DNA that has been given to me, most likely unchanged, in a direct line from Sarah through 125 years, 5 generations, and across 1750 miles.By sequencing a small part of the DNA I could identify from which branch of the â€œmaternal family treeâ€ Sarah descended.Based on the information I had managed to put together, I predicted that Sarah was a descendant of English immigrants who settled the Cayman Islands and would thus possess mtDNA belonging to a European lineage.
Senator Edward Kennedy (D-Massachusetts) proposed a piece of legislation before the United States Senate on 1 March 2007 called the â€œLaboratory Test Improvement Act.â€The Act is proposed as a series of amendments to the Federal Food, Drug, and Cosmetic Act (FFDCA).
Sen. Kennedyâ€™s statement(pdf) before the Senate, found in the Congressional Record from this month, defines his goal as â€œ[ensuring] the quality of clinical tests used every day in hospitals and doctorsâ€™ offices across the country.â€Additionally, he pointed out that the â€œtests are being used to diagnose illnesses, predict who is most susceptible to specific diseases, and identify persons who carry a genetic disease that they could pass on to their children.â€
The Daily American Newspaper in Somerset, Pennsylvania, recently highlighted a family surname study being conducted through a local forensics company.Â The Eustace/Eustis/Eustice surname Y Chromosome DNA study began in July 2006 and according to the news article the project has tested 80 men in eight countries, a remarkable number.
Ron Eustice, one of the leaders of the study and editor of the Eustice Families Post newsletter emphasizes the importance of DNA to his genealogical research:
â€œMost family historians have spent countless hours poring over genealogical records, trying to connect the dots.Â DNA testing is rapidly establishing itself as the newest and perhaps most reliable tool in the field of family history research. I believe that including DNA evidence is an essential part of family history research.â€
Argus BioSciences, located in Belmont, California, is an up-and-coming company offering DNA sequencing for the study of genetic genealogy.Founded in 2003 by Dr. David Whyte, the company offers mtDNA sequencing and haplotype determination.
Although Argus is currently (as of March 2007) offering only mtDNA testing, all products are being offered at a greatly reduced rate.Sequencing of the hypervariable region (which includes HVR1-3) is offered for only $125.00 (regularly $149).You can compare this price to those offered by other companies in my DNA testing company comparison chart.Additionally, Argus is offering complete sequencing of the entire mitochondrial genome (16, 569 bases) for $345 (regularly $695).The company will also accept four monthly payments of $95 to pay for a full sequencing (to inquire, contact Argus at firstname.lastname@example.org).Currently only one other company (Family Tree DNA) offers complete mtDNA sequencing as a regular product.
The last time I counted there are at least 21 unique companies offering DNA testing for genealogical purposes, either Y-chromosome, mtDNA, or autosomal testing (see the Sidebar to the right for a listing).Â To get a clearer picture of what each company offers I created a master list of every company and the services they offer.Â See here.
While compiling the list I also gathered information about the markers that each Y-chromosome test analyzed.Â See here.Â There are of course the standard markers offered by most companies as well as the markers offered by only a single company.Â What company have you been tested by?