Saturday, October 27, 2007

Ask The Genetic Genealogist

Dear Dr. DNA:

My cousin was recently diagnosed as having sickle cell trait. People who inherit only one copy of the sickle cell gene (from one parent) do not have sickle cell anemia; they have sickle cell trait. Her physician has told her that she "has a Black ancestor," but from my limited research on the web I have found several possibilities for the gene.

Sickle cell anemia is most common in people whose families come from Africa, South or Central America (especially Panama), the Caribbean islands, Mediterranean countries (such as Turkey, Greece, and Italy), India, and Saudi Arabia.

In the United States, sickle cell anemia affects mainly African Americans, with the condition occurring in about 1 in every 500 African American births. Hispanic Americans also are affected; the condition occurs in 1 out of every 1,000 to 1,400 Hispanic American births.

About 2 million Americans have sickle cell trait. About 1 in 12 African Americans has sickle cell trait. (This does not tell us how many of the 2 million with sickle cell trait are African American.)

Sickle cell trait can be inherited in the following ways:

-- Both parents have sickle cell anemia (inherit from one parent);
-- One parent has sickle cell anemia (inherit from this parent);
-- Both parents have sickle cell trait (inherit from one parent);
-- One parent has sickle cell trait (inherit from this parent).

My cousin is Caucasian. We are cousins on my father’s side. Both of her parents are dead; she has one sister and one brother, both living. There is an aunt on our father’s side and an uncle on her mother’s side that are living. There are many cousins on both sides.

Knowing that I am the family historian she has written me to ask if I have found any evidence of a Black ancestor on my father’s side. I have not. On my father’s side I have found nothing yet to indicate an ancestor that is African American, Hispanic, or an ancestor from any of the listed geographic areas.

So Dr. DNA, puzzle me this:

How could DNA testing shed light on this very interesting family history development?

1.Could DNA testing determine the ethnicity of this ancestor?
2.Could DNA testing determine if the ancestor was on the paternal or maternal side of her family, or perhaps both?
3. Could DNA testing determine the geographic origin of this ancestor?
4. Could DNA testing determine the generation of this ancestor?
5. How far back in time is it possible that this ancestor lived (100 years, 1,000 years)?
6. Who in the family should be tested?
7. What type of DNA test should be conducted?

I broached this question to a Sorenson Molecular Genealogy Foundation representative at a conference. He dismissed my question with, "Why do you want to know?" Why indeed! I am a family historian who has had a family mystery laid directly on my doorstep. Can modern science help me solve this mystery? Please, tell me more!



National Heart Lung and Blood Institute. National Institute of Health. “Who Is At Risk For Sickle Cell Anemia?,” Diseases and Conditions Index, ( : 20 October 2007).

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Blogger Lee said...

Great questions!

Evidence suggests there may be an African American in our ancestry, so I'm looking forward to reading the response you get from "Dr. DNA."

October 27, 2007 at 9:57 PM  
Blogger Janice said...

The best of luck in solving your family "mystery." Does your cousin plan to research her mother's side of the family? This appears to be the obvious next step.


October 28, 2007 at 7:33 AM  
Blogger footnoteMaven said...

I'm very anxious to see what Dr. DNA has to say.

And my cousin is hoping I will be so curious that I'll do the research.


October 28, 2007 at 9:35 AM  
Blogger Craig Manson said...

Very well stated and researched! Thanks for the education.

October 28, 2007 at 10:24 AM  
Blogger Nikki - Notes of Life said...

What a mystery. Looking forward to the response!

October 28, 2007 at 10:31 AM  

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